Looks like a lot of people here agree with this and have similar frustrations which makes me wonder - surely some of the developers working on these apps dogfood their own work, if not for any other reason than it's just very popular. The presence of these issues means that they can't fix them. Why?

I mean, I've seen this happen where developers legitimately want to fix little annoyances in the UI, but they can't. I think the reason why is a combination of two things. First, a mature product has to handle a ton of different scenarios making it a major PITA to change anything. If it's not a quick fix, it has to go trough the normal product process which brings me to the second reason - the product managers don't get evaluated based on how usable something is, rather it's some sort of an engagement metric. As long as the watched minutes go up, nobody cares if people are throwing their remotes in rage. So this is on product leadership, but maybe they just need better metrics, like a rage button on the remote.