[2019] Sony adds cross-play compatibility for developers who want to add it. Your move Wildcard.

Not really just in our court, but...Hello!

Disclaimer: I am speaking as a mod author myself to talk about this, and not in representation of the opinion of Studio Wildcard.

Regarding Crossplay:

Saying they support crossplay is cool, it may not necessarily be that easy though. Different consoles may have minor code and integration differences that can be large issues for consistency. The consoles might also have different rules that could make it difficult to appease all parties. There could be potentially any number of technical reasons preventing it as well, for any game. It's basically never just "A flip of the switch", and for some games, it may not even be possible at all.

Regarding mods:

They both allow mods in some capacity, this is true, but not the same capacity. For instance, Sony may have rules against running third-party scripts/code, which would completely prevent ARK mods from being on console due to the way modding works for ARK. HYPOTHETICALLY, if mod integration were opened up for the console versions they would still be limited by the rules of the most restrictive console for mod content especially if we had to support crossplay as well. Otherwise turns into a pretty complicated matter where people are unhappy about why X console gets these certain kinds of mods but none of the others do.

Regarding mods there are other problems, mods still would have to follow certification rules for every console they would be published on, so someone has to certify them, all of them, for every single update they do. I'm sure that alone can't start to paint a picture of potential problems.

There is also another technical problem, this one assumes a hypothetical world where all types of mods are allowed. While some console might provide easy access to devkits, others do not, this makes it really difficult for mod authors to debug any kind of console-specific issues. In fact, it reduces it almost entirely to guesswork, not a great way to try and solve a problem.

Distribution is another difficult (yes solvable, but it's very costly to do so) problem. Currently, no console provides a distribution platform for mods. This means that studios have to build a distribution and download system into the game itself. Basically recreating the steam workshop functionality in-game.

But there is one more, probably the most important hurdle, I never see anyone ask mod authors themselves, if knowing all of the above, would want to put their mods on consoles. When we did the S+ integration, we purchased the mod from the author. These are their creations, their time and effort, ultimately they have a right to say "no, I don't want to deal with the hurdles"

While the console platforms have slowly been inching towards being mod-friendly in recent years, they still really aren't even close. I would estimate that at the soonest we are looking at another couple of console generations out before they've reached a state of "sorta mod-friendly" as a platform.

Be aware that this would also come at a cost, making consoles mod-friendly means you are giving up the reasonable expectations that the consoles will keep your data secure or that the games you play will behave in expected ways when using them. (Using mods is, will, and has always meant taking a certain general degree of risk and studios are not responsible for what happens when you use them)

All of this is not to say one way or the other whether consoles and studios should support mods and cross-play. This is simply information to see why any given studio may decide not to do so, and the hurdles that they will have to face if they do.

I don't have any recollection of this claim, but all of that was before I joined the team.
If it was said, I would have to imagine it was in relation to Xbox/Win10 versions, there might be some aids to facilitate crossplay in that regard.