I will agree that what Sony did with not honoring old download codes is really shitty. It's not like Crunchyroll bought Funimation and then nuked the codes. It was Sony (who already owned Funimation), bought Crunchyroll, and then nuked people's Funimation codes. It's like... wut? Though this is the same company that owned two streaming services, and still had their stuff split between them for years.
Sadly I think the problem with streaming and exclusive content is that I don't think there's much to do besides exclusive content. It's like video game consoles, where there isn't much going on besides having something nobody else has, but worse as there's no specs to worry about. Monopolistic competition is kind of the only way to proceed, especially with something as fickle as licences on media.
Someone like Sentai Filmworks would benefit from having their shows on multiple platforms, as they're just a license holder, and release physical media. Whereas Sony owns both the shows and the streaming service. They don't have to worry about fiddle around with license agreements with some third party company. They can just go "oh, I own this show" <hits upload>.
I also don't think the anime streaming market was really ever that competitive. The anime streaming world was really just Funimation vs Crunchyroll, with Netflix getting one or two big name shows a season (at best), or you go there to watch old shows from several years ago. Even for a long time, Crunchyroll was the only place for up to date content, and Funimation would license it awhile later and Crunchyroll would pull it.