Over the last week we've had a lot of people try and explain to us why allowing crossplay would be bad for Sony's corporate interests. You'd think a simple consumer with no stake at a company wouldn't give a crap about said company's corporate interests. You'd think he or she would be more concerned about his or her own interests. You'd think he or she would push for a feature that has nothing but advantages and literally zero disadvantages. I have this to say to them.
Crossplay, as a feature, benefits you, the consumer. You can play with all your friends without buying more hardware and enjoy a much larger pool of players for matchmaking.
Crossplay, as a feature, benefits developers. It maintains a game's multiplayer population at much healthier levels over time and it increases game sales across all platforms because low multiplayer population is a frequent reason to skip on a game if you only own one platform.
Crossplay, as a feature, doesn't benefit the market leader so they don't allow it. They don't care that it benefits developers and they don't care that it benefits you, they only care about themselves. So why do you care whether or not it benefits them?