Because those systems already exist for the console players. All they’re doing is switching it over to steam but they likely had a translation layer there before to do all the things you’re saying but through PSN instead. Why? Because that system already exists for consoles.
So their options here are that they can take the netcode for consoles and modify it to utilize SteamIDs and fetch data from Steam or they can just turn your Steam ID into a console ID and treat all of the inputs to their systems exactly like they would on the PS5 while fetching them from Steam.
I’m not saying it’s a good idea, I’m saying you’d think that just trying to match the console and the way it handles players would be simpler. Especially when you’re trying to make cross play work. Clearly it wasn’t so they temporarily ditched it. Maybe Sony does just want your data but if that’s true, why would the telemetry gathering be such a big deal? And they also could just use your SteamID for that data gathering. So clearly PSN used to be more integrated than people here are suggesting