It's bewildering that this is such a loud issue online all the sudden tbh. Like YES full cross play would be better, YES Sony isn't doing it because they're the market leader. Totally agree. But it barely affects my life. When I'm playing Rocket League, I hardly care if my opponent is on PS4 or PC. I feel like this is primarily a push because Xbox One X is objectively the best console hardware right now, and lack of access to the largest online community is a big reason not to get one. Cross play between console and PC is still a relatively new thing, so I'm surprised people suddenly expect full cross play between all consoles. I support it, I agree Sony is being anti-consumer with their policy, but also I don't really care.
It seems weird that this is suddenly the hill to die on and not (for example) ending console online gaming fees, or the PSN name change issue.