Why is cross-platform play so rare?

Why is cross-platform play so rare?

How is this not a thing?

 If you have any gamer friends at all, you're probably familiar with the problem of cross-platform compatibility. Maybe you bought Destiny 2 for PC, and they bought it for Xbox One. Or you bought it for Xbox One, and they bought it for Playstation 4. Too bad - you'll never be able to play with each other, because each platform is its own "walled garden."

Here's the crazy truth: There's no technical reason that prevents cross-platform play. 

Now if you're talking about PC players and console players sharing the same world, there is a factor at work here. Several games have set up cross-platform play between PCs and consoles, and they have all discovered that the faster response time for a PC player with a mouse and keyboard means that they have an unfair advantage against console players.

Of course, that's only an issue in competitive multiplayer games. There are plenty of  other types of multiplayer games where faster response time isn't an issue. It's not an issue with collaborative mode games like Minecraft.

And of course, gaming companies can always compensate for "the mouse advantage" by handicapping PC players to slow them down to average console players' speed. 

Honestly, I wouldn't care if my PC friend has a faster aim time. I would happily be a little bit slower on the draw if we could play a game like Borderlands 2 together.

The real kicker is Xbox/Playstation cross-platform play. It's not a thing, because Sony said so, that's why. There is no technical reason preventing Xbox and Playstation people from gaming with each other. Microsoft has even said they would be open to this. But Sony has given a "hard pass" on the very concept.

Funny that an industry which usually goes the extra mile to cater to the whims of its clientele is so entrenched on this issue! Well, maybe not "funny."