Since this post and the ensuing answers seem to be about me (and apparently, I missed this whole thing!) I thought I would add my voice here - albeit a little late - to the discussion just to clarify why I did / do what I do.
Concerning Alex's post, I honestly wasn't even thinking about semantic spelling localizations - I merely thought the words were misspelled and was correcting for error. I believe Tim referenced that some people act as "teachers" on the Music SE, and I can't help but feel as if that was directed towards me. I am a teacher by profession, so I'm always looking for ways to help clarify information for others. If I legitimately had questions that I thought would be best answered by the Music SE, I would post questions. The majority of my quandaries are composition related and very specific and wouldn't be helpful for the site. Also, like most people I suspect, I usually am able to answer my own questions with a little bit of research. But I digress.
I don't edit grammar in posts to be "grammar police" or to try and put my stamp on everything. This site serves the larger good of the internet, and I believe that if someone comes to the site looking for answers to their questions, they should be able to read the question / answers with correct grammar and presented in a clear, professional way. It only hurts the Music SE's credibility and reliability for information if visitors have to wade through piles of internet slang and sentence fragments. Further, by having clear communication of ideas (through correct grammar) it minimizes variables that can interfere with learning. And really, when you boil SE down, it's not about the individual subjects, it's about learning.
As NReilingh mentioned in a comment, SE is collaborative, and just because I make an edit on something doesn't mean that my edit(s) are the end-all be-all. I encourage people to change or revert my edits or any other edits as long as they are constructive and attempt to improve the answer or question. Edits I do are not out of hubris, but out of the desire to present a question or a solution in the best possible circumstance.
I whole-heartedly agree with "respecting the original author," however, there is a difference between re-writing an entire question to suite one's own voice and changing simple conventions. I have taken two surveys about Music SE's credibility (and I'm sure others have taken more,) but in reading the questions and answers, I can't help but say that though I agree that international and local language conventions should be respected, those who are posting answers / questions have a duty and responsibility to present their own information in the best way possible.
I've understood this site to be an attempt at being a more professional exchange of information than a forum. But if high standards are not held, what then really differentiates this site from other resources?
Now, I may have over-stepped my bounds editing-wise, and if I'm posting too many answers and you all think I'm a conceited know-it-all, then I can't influence your perception of my intent no matter how earnest or honest I may be in my endeavor. If I've over-stepped, then I sincerely apologize for doing so without realizing. I won't apologize however, for attempting to make Music SE a better place. We should all be holding one another accountable.
Okay, I've said my piece. My response may be a little much, but I care passionately about music and about education, and I just want the best for other people.