All I want is shuffle not to repeat until I've heard (or skipped) every song.

I mean really what they should do is provide some degree of control over the shuffle parameters... But hey ho, back to listen to whatever Spotify thinks is my favourite song.

Humans are really bad at understanding randomness

Not all of us. I can't imagine not understanding that if something's random, there's a possibility that something like playing the same artist five times in a row might happen. It's cute when that happens, it's a thing that should be possible and one of the things that was so much fun about shuffle.

I don't want to be that guy either, but do you have a source showing that people really did complain about this? I've heard it said so many times that they did, but I don't believe it. I think it's just an excuse for big corporations like Spotify and Apple to manipulate algorithms to deliberately promote certain artists. I don't believe it was ever well intentioned, and I resent that there's no feature for people who want "shuffle" to work like it should work -- in a completely random fashion. Or at least give us the option. The fact that there's not even a randomization option at all should make clear that this was not development that was done in good faith or for the benefit of the listener. They actually removed a feature in order to promote their corporate crap.

It's so obvious that Spotify is promoting certain artists. As soon as I launch the app, it's always the same shit on the front page. At this point, I could pretty well predict what major-label crap is in all those "recommended" playlists they create for me. It's so bad. Honestly, if it weren't so damn inconvenient to do so, I'd just rip songs from the CDs I buy from independent labels and put them on my phone. I'm pretty sure there are some apps that have a genuinely random shuffle. Just got to find one.