Ok, so here's the thing. I can totally understand if something has little meaning to you because it won't affect your gaming in anyway whatsoever. That's completely fine.
What I don't get though, is that if it won't affect you gaming either way why default to an opposing position? It doesn't take a whole lot of imagination to envision how with tens of millions of consoles from other ecosystems out there, how a good chunk of those are owned by groups of friends with different platforms.
It's not even just a case of close friends and family either. Within communities for niche titles, platform borders can make it extremely difficult to play the games in any capacity at all. Stuff like this isn't at all uncommon:
(They're trying to play Virtua Fighter 5 Final Showdown)
Now, obviously it's too late for a game that was released last gen, but this is something that will continue to happen to smaller games going forwards unless crossplay becomes something expected as standard.