I don't know, there's probably not a singular reason. For one, many are just consumers/users and not actual devs, they only want "open source" because people told them to want it, or they think it's safer or has a better community or something, but many times they don't actually want it for anything useful besides being able to say it's open source, even though they never contribute anything. I think these are the kind of users who always demand ridiculous features and way too much time from the real devs.

I've also seen other devs that just had wildly different views on fundamental parts of a project, or had unrealistic expectations, or just lived in some kind of fantasy world that most people disagreed with.