I can understand why those who meet or have the opportunity of meeting might use their real names. As I’m more than 3000 miles from most, my real name is immaterial; it neither adds nor detracts from what I post here or elsewhere. My real name, however, is uncommon and a Google gets me 9 out of the first ten hits, most of them in my professional capacity.
Some others might post from their work locations, where an employer might have an electronic mail/internet policy e.g. Access to the Internet is provided to a user as a company business resource and should be used for legitimate business use only. It is understandable that some here in that position would prefer to "hide."
That is why I remain anonymous and why I have no issues with those who are of a similar disposition. (Provided they are polite and do not post drivel.)
K.