There is sometimes a reason people won't do that. For example with one piece of software I'm aware of, in order to open an issue you have to first fill out a form that says you have performed several tasks first, half of which are things many users would either not know how to do or would find very difficult. In another case, in order to report an issue the developers want you to include a huge log file that may contain personl or private information that you don't care to reveal to the world, and they don't give you any way to send it to the developers privately.

So, people who are put off by such demanding requirements to file an official issue will often yelp about their problem in a forum instead, hoping that perhaps some other user has experienced the same issue and can tell them what to do without necessarily getting the developer involved.

And when you say "Devs are humans", I can tell you that sometimes we users seriously question whether that's true! There is one dev I am convinced is a parrot because he only knows how to squawk "debug log" whenever anyone mentions an issue.