Most streaming services commission their own content, yes, but they do so to market original content - Netflix Originals don't pretend to be Wes Anderson movies, and get slid into your playlist when you aren't looking

The only evidence I can find is with Spotify doing this.

A) It's not how every streaming service does it, and B) this is whataboutism. Even if it was true, it doesn't make Spotify less shitty.