What is the purpose of random encounters?

[kyoryu]

but in practice that is not how it works. We have to listen to the DM describe each hour while a random encounter check is rolled.

It should be. It has been in the games I've played that used them, or at most 10 seconds of description.

I don't think "people can do it badly" is a good reason not to do things, if they have value outside of that. I'm sorry you had that experience, though, it sounds exhausting.