I don't remember the exact words and perhaps the moderator who removed my comment would care to explain why he did so and paste my comment somewhere on the thread.
In this answer I left a comment saying I didn't understand why Muphrid's comment had two upvotes (which it did at the time) and I added that his comment added nothing to the answer except for naming the notation. Furthermore I mentioned that $\frac{dx}{dt}=x'(t)$ is wrong and that it should be $\frac{dx}{dt}(t)=x'(t)$ or $\frac{dx}{dt}=x'$.
My first remark was more of a request for clarification because I really couldn't see why someone found the comment helpful.
Do moderators have carte blanche to remove comments as they wish?