Phil Spencer, the head of Xbox, expressed his desires for PS4 and Xbox to be able to cross-play together. This leaves us to assume it was most certainly a decision on Sony's part to not allow it. Previously Sony had explained that their decision to not allow cross-play was to "protect their players' security," but they have chosen to not make any comment on why they're deciding to stay out of such an inclusive platform game.
If you want to use cross-play, don't link your account to PlayStation 4
If you create a Fortnite account and link it to your PS4, it will not allow you to log in on any other platform besides PC. This means you'll be required to make a separate account to use on another platform. If you are a new player looking to get into Fortnite who intends on using the crossplay options make sure you link your account to anything but your PlayStation.
Basically, if you want to use the cross-play options then don't link your Epic account to your PlayStation 4. You don't want your account locked to a PC and PlayStation when you have so much more abilities to play with a lot more people by keeping it connected to literally any of your other platforms. On top of this, your PlayStation 4 account purchases don't transfer to your Xbox, Switch or PC accounts. But, if all your friends are playing on PlayStation 4, and you have no intention of linking it to another account, then you have nothing to worry about.
Unlinking your Fortnite account from PlayStation
There are a few warnings we want you to know before you do this. You will lose just about everything connected to your account as you can not carry it from one console to another. These warnings and instructions will work for PSN ID, Nintendo account, Xbox gamertag, or another external account, not just PlayStation.
- All of your saved data lives on your Epic account, not your connected account.
- If you disconnect your PSN ID from the Epic account that is currently connected to, any purchases, stats, and saved data will be lost.
- Platform Locks on Fortnite cannot be circumvented, even by replacing one connected account with another.
If you've read the warnings and still want to disconnect your PS4 account so that you can connect it to another platform:
- Go to your Connected Accounts page.
- Click the DISCONNECT button below the external account in question.
Now your account is free to connect to any console you so wish to connect it to.
June 12, 2018: We've updated this article with information on how to unlink your account, although it's not advised.