I was recently browsing EE.SE and came across this revision (Revision 2) by moderator Nick Alexeev on this question. I understand the revision of the tags, but I'm wondering why the simple "Thanks for your help!" on the bottom was removed. The text doesn't detract from the quality of the question as far as I can see; it's something that I myself have written on my answers and questions. Is this revision proper formatting of an SE question, or was it an unnecessary edit?
It's superfluous text. Greetings and salutations on questions are routinely edited out because they clutter the Q & A goal of Stack Exchange. AFAIK it is done on all stacks, atleast the four I've been on regularly.
Meta.SE on the subject Should 'Hi', 'thanks', taglines, and salutations be removed from posts? is a bit contentious, not everyone agrees, but the powers that be (Stack Exchange employees) dislike them.
Greetings are automatically removed by the system when posting. See employee Jeff Atwood's answer there (second one).
Thanks are implied, and should be shown via up votes and accepting an answer if appropriate.
If anything, you can always leave a comment on a good answer to say thanks (but those get trimmed eventually too). SE, all work, no play.
Because someone decided that there is something wrong with common courtesy. Frankly, I find it silly, and a waste of effort to edit such things out.