This is pretty much normal in forums, Facebook is to some extent the odd one out I think. I've worked in computer forums as a helper and I'm also a small arthropod species identifier in the Natural History Museum forum, and in all cases the members have mainly been identified by nom de plumes.And of course, in most cases, you can actually see the poster rather than some strange i.d’s and profile pics.
I always use flecc which is the first part of my Italian surname, so not totally anonymous.
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