To clarify, it's about quality
and file size - I find that some pirates do a better job of offering high quality videos with better compression (and thus smaller file size). Especially if they use more modern codecs like HEVC. (And right now, I don't really care about 4k quality or Dolby vision). The ability to watch it offline (without any nonsensical 24-48 hour limitation) in
any device is the real pleasure (I used to be able to connect my iPad to my TV to watch some series on Prime, but they annoyingly disabled support for that).
But as I also mentioned, all the above pales in comparison to their plan to spy and profile us to serve us ads, when the very reason that people have dumped TV and pay a premium for streaming platform is to avoid advertisements.