There are a handful of games on Switch that you can enjoy online with players of other platforms. Hop on there and play alongside players on Xbox One, PC, and mobile. That's not the case when it comes to the PS4. Sony has blocked cross-platform play with Switch and Xbox One owners. Sony released a non-response about their stance on cross-platform play, leaving many wondering why the company is being so stubborn. Former head of Sony Online Entertainment, John Smedley, has shared some insight on the situation.
When I was at Sony, the stated reason internally for this was money. They didn't like someone buying something on an Xbox and it being used on a Playstation. simple as that. dumb reason, but there it is.
Not exactly the reason many people were thinking, but there it is. Obviously Sony may outright deny this or not even bother to comment, but I think we can trust the word of a former Sony employee on the matter!