I've both had and followed these same, circular discussions on said discussion platform when the Fortnite issue boiled up before and after the Switch client's release. As user of a GaaS I don't give a Pennyless Trader's behind how much Sony wants to wall in their userbase even with GaaS games developed by not Sony-owned teams, like Frontier, nor do really think that anybody should be waiting for Sony. Who've by the way opened the Pandora's Box with Fortnite by setting precedence, proving that their policies are holding up progress and nothing else. The "but let's not make a habit of it"-part doesn't work. Because I can very well make a habit of going to one of the other platforms the game is on. Much easier so, than selling PS4 to all the circle of players who might be playing on other platforms already, so we can play together.
Other example of GaaS with crossplay that adhere's to Sony being the spoilesport: War Thunder. PS4 to PC and PC to XBox crossplay is implemented, but anything involving PS4 and XBox isn't allowed. That's one way to go about it without waiting for Sony to catch up with the times.
Or really, just leave the PS4 out of it and implement the features for XBox and PC. it should be the PS4 users' and Sony's loss, not the loss of XBox and PC players or Frontier, whose business model should be to grow and strenghten their Elite userbase, not to give Sony a backrub.
If Sony's the spoilsport, the joke is on them. Here's a wonderful marketing piece from Nintendo and Microsoft indirectly mocking Sony with the mere fact that they're not as stuck up with their crossplay policies:
It's not the customer's job to make the excuses for Sony. But Sony sure lets all of those who did look like fools, having caved with Fortnite.