You're right. I tried to touch on this
earlier. The explanation that's frequently repeated is that "If Sony opens up cross-platform play, then someone would no longer need to buy a PS4 to play with other PS4 players" and that this somehow would encourage them to buy an Xbox One or Switch instead.
Well, the converse is true, also. If your buddies happen to play on either Xbox One or Switch, then you
cannot join them if you're playing on PS4...meaning that if you're in the market for a new video game system, the PS4 is your least likely choice.
With that in mind,
it harms Sony more to disallow cross-platform play, than it allegedly "helps competitors" to allow it.
Shouldn't the "market leader" have market leading features? Why should they deliberately cripple the feature set on their own platform? This ill-advised move instantly gives both Microsoft and Nintendo a competitive advantage over Sony--one that they didn't have just a few days ago.
But holding back features does make sense? How?
I understand Microsoft might have been stubborn or "the bad guy" about this in the past. That's not their position
now. Their motivation for changing their stance is irrelevant...the bottom line is simply that
they changed their stance, and their customers benefit from it.
Sony can make all of this bad sentiment go away in an instant if they do the same thing.
That is also a good point. This is clearly short-sighted. Better for Sony to correct this error in judgment ASAP, than to let it stew and watch consumer and developer sentiment turn more and more sour.
I would not be surprised if there are people that have read or heard about this decision, whose future video game purchasing decisions have
already been influenced
away from Sony as a result.