[1] e.g., https://en.m.wikipedia.org/wiki/NProtect_GameGuard
I would imagine Wine is in a similar predicament.
It seems far more likely to that most players are just using Wine for its intended purpose—to play Fortnite on Linux.
Of course, it's possible (if much harder) to go in and hack up the DLLs on Windows. Anti-cheat addresses that by whitelisting known-good MS hashes and/or requiring some type of signing. There's a lot more overhead involved in doing something like that for WINE, since every distro's build would be different, it's common for users to have their own builds with game-specific patches enabled, etc.
I've been out of the WINE scene for a while, but I'll say that I don't believe many WINE users are trying to exploit the platform to cheat. I think it's purely a cost-benefit tradeoff. The vendor doesn't feel supporting a legitimate WINE use case is worth the expense of figuring out a reasonable way to validate behavior, handle integration with distro builds, support debugging/custom patchsets, etc.
their method (blocking Wine) is questionable though. it reminds me of websites that block Central/Eastern European IP's "because of bots" (yeah, it happens). the goal is nice, but the method hurts many honest users.