Destiny 2 could have had cross-platform characters. At least that was Bungie's wish during development, according to Kotaku's Jason Schreier, who claimed as much in the latest Splitscreen podcast. It seems like Sony, which still owns some exclusivity rights for Destiny 2, denied the opportunity.
I heard that Bungie wanted to do character transfers for PS4, PC - before Forsaken came out - but Sony wouldn't allow it. Sony is just like, we want people to associate Destiny with PlayStation 4, even if that means screwing over other players. It sucks and hopefully Bungie ends it.
Schreier's sources are usually spot on. Besides, it would be far from the first time Sony has openly opposed cross-platform features. Many developers and publishers have spoken against their policy on this matter, which still seems to be largely set in stone with the two exceptions being Fortnite and Rocket League.
As to Destiny 2, it is now fully in Bungie's hands after the developer parted ways with Activision a few months ago. The last expansion, Forsaken, already managed to win back some disgruntled fans. Here's an excerpt from our review:
Forsaken makes some smart changes to the Destiny 2 formula. Killing off Cayde-6 kicked off Season Two in a big way with more content every couple of months for the rest of this year heading into the summer of 2019. Destiny 2: Forsaken feels like Bungie has found a way to please both the casual and hardcore player, at least for now. Still, as much as I really loved my time with Destiny 2: Forsaken, I can see some new players being slightly intimidated by the content and not being as emotionally invested in some of the more emotional story beats.
Destiny fans are hopeful that Bungie will be able to engage with the community more directly and follow its feedback more closely than it could ever have when it was tethered to Activision. We'll see whether that's the case in the future.