I have heard complaints where I work that less-technical foks find the UI unpleasant/confusing. I think it is due to a combination of the keyboard shortcuts being front-and-center and the threading model seeming "complex" (really, just logically structured)
I'm not sure there is a strong/good argument against it, though. e.g. word processors are "more complex" than text files for sure, but people have learned the benefits of those.
I think the education / user-onboarding flow could be improved perhaps.
The usual complaints I get (as an admin of an instance) are:
1. "Hard to search"/"Can't find anything".
2. Off-topic responses because people post in whatever the most recent thread they used happens to be (results in (1)).
I like it, though, due to having some similarities to a forum.
I'm not sure there is a strong/good argument against it, though. e.g. word processors are "more complex" than text files for sure, but people have learned the benefits of those.
I think the education / user-onboarding flow could be improved perhaps.