They've also contributed significantly to open source tools for video processing, one of the biggest things that stands out is probably their VMAF tool for quantifying perceptual quality in video. It's probably the best open source tool for measuring video quality out there right now.
It's also absolutely true that in any streaming service, the orchestration, account management, billing and catalogue components are waaaay more complex than actually delivering video on-demand. To counter one thing you've said: mouse movement... most viewing of premium content isn't done on web or even mobile devices. Most viewing time of paid content is done on a TV, where you're not measuring focus. But that's just a piece of trivia.
As you said, you just don't like them, but they've done a lot for the open source community and that should be understood.