As you may know, moderators have access to certain statistics which aren't otherwise easily visible (though which are largely retrievable from either the SO data dumps or data.se). I have also perceived more closures and deletions than normal, so I thought I'd take a look at the data. We are asked to not share specifics (I don't know why), so these are averages.
It turns out that somewhere between 8% and 9% of posts (questions and answers together) are deleted each week this year - closer to 9% now, closer to 8% in January. Last year, It hovered between 6.5% and 7%. So there is a definite increase. To me, it feels pretty noticeable.
In many ways, I find the SE platform to be well-designed for self-governance. I rarely disagree with people deleting answers - it seems to me that people rarely delete answers without good reason. But some people target some questions (and their answers fall because of it). There are three ways to delete a question (edit: as is pointed out in the comments, I'm slightly off here. See the comments, but it doesn't change the discussion):
If the question is negatively scored, more than a month old, and there are no upvoted answers, then the Community user will delete the question automatically.
A number of users puts the question on hold. If it is not reopened in the next 5 days, the question becomes closed. Once the question is closed, 3 10k users vote to delete.
A mod uses mod superpowers to delete the question.
Issues with the first way would be decreased if more people voted. Something that I've noticed much more than closures and deletions is that the voting has not at all kept up with site growth. Unfortunately, while we can sometimes say vote early, vote often, a very small group of users reads the meta and fewer care about what they read - this is very hard to change.
The ideal resolution of the second way is for users to edit their
on hold question. It gets put in a reopen queue, and users tend to be pretty liberal about reopening after any nontrivial edit from the queue. Frankly, though, users very often don't edit their question. Or if they do, they're confused - they have no idea how to approach the problem, users demand
context, and they edit something in like
I'm lost. What do I do?, which typically doesn't lead to reopenings.
Something which could be done, but which isn't done very often, is for capable users of really editing lower quality questions into reasonable questions, especially questions that have been otherwise abandoned by the OP. For example, it seems to me that it's extremely likely that an answer of André is great, and the site is better off with it than without. If the question is enroute to being closed, then perhaps a higher rep user could really edit the question. [This conforms to the view that this site is a Q&A repository, where good answers to good questions should be kept so that they can be found later; a different popular view is that this site is for learning math, and thus answers should help the OP first and foremost, including limiting to hints and whatnot]
To try to answer your actual question, Martin's Link in the comments contains every site that I know of aside from reddit and quora. I've at least looked at all of them before (and migrated here from mymathforum), and I really think MSE and MO are the best at what they do (i.e. not discussion).