It's not really up to Sony is it? I don't understand why they are ok with pc crossplay but when it comes to competitor consoles they are against it. If anything they can just separate the ps people to play by themselves and let everyone else enjoy it together on the other consoles if Sony won't rip the stick out of its butt.
I thought its because microsoft wants you to have an active Gold account to be able to play it , and SE dosent want their subscribers to have to pay an additional fee on top of the game price.
It says on the in article link that Sony is saying no because they "have an online contract with their customers" and "are worried about exposing young children to other networks".