large Minecraft servers (e.g. Hypixel) have *pretty good* anticheats, but they're fundamentally limited by "the vanilla client doesn't always cooperate in all the ways we want". you can do a lot better than peak Minecraft anticheat, in games where the developer of the game considers server-side anticheat when building the game, and doesn't let the client assume things that it shouldn't have authority over. like, if the vanilla client was more "well behaved" you can definitely do a lot better, without it really impacting the gameplay experience, and certainly without the client being at all invasive (i'm *not* pushing for things like kernel-level anticheat here, to be clear).
at its extreme, you get Rocket League, whose networking model is basically "send us your inputs every frame, and server will send you back the state of the world". minus the fact that *wallhacks* are mostly irrelevant in that game (occluding world state is a difficult problem that this game avoids!), it's basically impossible to cheat in such a model without just *automating your player entirely*. the only method of cheating becomes a bot which cannot fundamentally do more than the most skilled human. and making that bot *is really difficult*.
vanilla Minecraft client kinda assumes it can just teleport at will. with ghost blocks and packet loss, "illegal movements" are not a surefire sign of cheating (packet loss abused in the "Blink" hack). but it's possible to design a networking model where "illegal movements" (such as teleporting) is fundamentally not a thing the client can even ask for.