not realy just vita and ps3 though even those are different ps3 you actualy CAN use without an psn account unlike the vita
with ps4 and ps5 I am pretty sure you need to login the same way though I am not 100% on that since I dont own either of those systems
I don't have a PS5, but with PS4 you didn't have to do any of that. That's why Sony's website only mentions the two older systems, not the newer ones. it was a feature designed to enhance security on the older, outdated systems. It was only PS3 and vita, but you are right, you can play PS3 w/o an account.
My 2nd account can log into PS4 no problem, because you didn't have to go through these hoops.
cant you use your ps4 then to find your password back so you cna use it on your other account on the vita? at leats that would solve your issue
and lets be real its not about security at all sony doesnt give a fuck about that
its just to literlay kill their legacy systems. they tried it before by closing the stores people got mad so they ecoinsidered now they are just oing it in small steps