Why do tv show/movie subreddits ask so many questions that seem to misunderstand how fiction works?

I'm reasonably new to Reddit, under a year regularly browsing, and I've noticed this strange trend. There are many posts, often in sitcom subreddits, which seem to ask questions as though they are about real people. Sometimes the question is something like 'why would [character] do [part of plotline that creates tension or conflict]'.

What I don't understand is that this is a fundamental part of how fiction and storytelling works. Is it an attempt to reconcile favourite characters not being 100% good all the time? Or a genuine attempt to understand behaviour that's an exaggerated version of real life? Or is this just an evolved rhetoric that Reddit has developed over time?

No disrespect to anyone who does post like this, I just don't understand!