Were two users removed within the past hour?
Why do they do this? Are they somehow offended by something happening here? If so what sorts of complaints are typical?
This really isn't an answer to the present question, but I don't want to clutter up the comments, and it does speak to the "fall out" that occurs when a user asks to be removed. And given the lack of communication from the two users who asked to be removed, I am going to speak up and speculate a bit: I refrained from participating at Math.se for nearly a year - in part - because of issues I will address shortly. I did not choose to remove myself when I decided to "walk away".
But the absence of most users @ math.se goes easily unnoticed. I'm sure my lack of participation went unnoticed. In contrast, given the question at hand and the ensuing comments, the absence of the users who chose to remove themselves from math.se, or at least one of those users, did not go unnoticed.
Thought: perhaps a user, "high-rep" or not, may be trying to make a "statement", so to speak, with respect to his/her departure, which may not be noticed otherwise than by asking to be removed. Likewise, as I am currently feeling rather ambivalent about math.se and my perception of the dynamics that play out here, if I ask to be removed, it will likely be noticed because I have cast a lot of upvotes!
There are less than desirable dynamics occurring here at math.se that have nothing to do with the quality, or lack thereof, of questions and answers.
First, I suspect - without pointing fingers - that there is a "likability" factor which contributes to voting patterns which doesn't say anything about the quality of an answer, question, or comment: voting patterns that reflect personal biases having nothing to do with the quality of a particular question and/or the veracity and helpfulness of a given answer. Despite the fact that math.se is purportedly for math Q&A, voting patterns (at least as I see it) reflect much more than mathematical veracity and/or helpfulness.
For example, I've seen - on more than a few occasions - some of the most high-rep users post an incorrect answer and yet receive a handful upvotes within one minute of posting, even when others have already posted correct answers and yet, remain deprived of upvotes. In other words, if we let $Rx$ represent "$x$ has high rep", $Ux$ correlate with "$x$ gets an upvote", and $Lx$ express "$x$ is likable or well-liked",
then I am suggesting that it is not necessarily the case that we can then assume:
$$\exists x(Ux \rightarrow Rx).$$
I suspect that the converse also plays out here:
$$\exists x(Rx \rightarrow Ux)$$
$$\exists x(Lx \rightarrow Ux)$$
(Note: I have taken the liberty of using $\rightarrow$ in a semi-causal sense..., which cannot be captured by "strict" implication.)
Also, it seem there are many occasions in which a sophisticated answer assumes far more advanced mathematical maturity if it is to be of help, which receives a handful of upvotes because the answer correlates with the upvoters' level of understanding, but which are plainly way over-the-head of the OP (i.e., answers which assume knowledge which is far beyond the scope of the OP's level of education, and hence, may be horribly confusing and thus unhelpful to the OP). Granted, for future users, those answers may be helpful, so I'm not implying sophisticated answers do not belong; rather, I'm observing that votes often seem to correspond to "who outwits others" vs. who is most helpful. (I am reluctant provide links to such questions/answers because I do not want to "finger-point" anyone!)
Granted, there is meta-math.se to make such a statement (of "washing ones hands of the site"), but then a "disgruntled" user has to deal with the possibility of a barrage of "downvotes", which would only further discourage him/her.
$(*)$ Assuming that a disgruntled user does not want to "go public" to discuss an issue, ideally we would like him/her to contact and/or flag a moderator to discuss it before officially asking to be removed altogether.
Otherwise, if s/he is determined to be removed, perhaps there should be two other options, so it's not an all-or-nothing matter:
$(1)$ the option of negating the impact of his/her participation here, in terms of previous votes, and
$(2)$ the option of being removed while leaving their votes stand. Could this be a feature request? Some who want to be removed may very well not want to deprive others of the rep corresponding to his/her upvotes.
To end (yes, I'm going to wrap this up!)
I suspect there are many users whose participation consists mostly of voting, editing, and/or commenting - all of which are welcome and valuable. If we value such contribution, so long as such users have the option of being removed, along with their votes, the math.se community is held accountable, to some small degree, to keeping this site a welcoming arena in which to participate.
We're obligated to remove user accounts and personally-identifying information upon request. While we do try to avoid this (if the person is willing to share his reasoning with us, we'll try to mediate disputes or correct problems), often it is too late by the time we're contacted.
And yes, two accounts were removed upon their owners' request yesterday.
We do try - particularly in the case of older, high-reputation accounts - to work with the folks requesting deletion, to see if a less destructive resolution can be found. However, they're under no obligation to work with us or provide us with any information beyond "this is my account and I want it gone".
My advice to moderators wishing to avoid this is to not let it get that far. If you're letting a situation degrade to the point where someone feels they're unwelcome here, you've already missed your best chance to mitigate the problem - so don't sit around waiting to hear from us, get in touch with the person and try to fix it. Leaving an annotation on the profile is a good idea as well - we do try to investigate these before taking any action, but if there's nothing visible this fails; whether or not we'll take the time to involve moderators at this point depends considerably on what information we're able to garner from the account itself or its owner.
I actually do not see any reason why any serious user should ever be removed.
The effect of deleting a user seems to be that that users account profile cannot be visited anymore, the username changes to userXXXX with the Xs representing digits, the votes get cancelled, and the user cannot use the account anymore. If we, as a community, decide that the cancelling of votes is undesirable (except for sockpuppets, spammers etc.), one can just change the name of a user, delete all profile information and the moderators suspend the user indefinitely.
Do moderators have to respect removal requests?