computerised opponents

That pun you made is exactly what I say to opponents in the chat when I suspect cheating

How do we know?

How do we know we're not a brain in a jar somewhere, and reality isn't just an illusion.

Ooooh, spooky.

I admit it, I am a robot that was designed to only make you feel as though you were playing against a real human when you play against me. I am sorry to have disappointed you. How did you see through my and my fellow robots cunning disguises?

Catch and "feel" are different.

In the early days some cheating idiot sued (or threatened to sue) chess.com because she might lose students, so chess.com has to be careful. (Yelena Dembo)

But it is easy to feel the most blatant stone age idiot cheaters. I've reported them before and they're usually banned within a few days (sometimes a few minutes!)

But people who put effort into cheating + aren't total idiots at chess (and programming) can be basically impossible to catch, by chess.com or anyone else... so you'd want a sophisticated way to try and catch them (like chess.com has). You couldn't use advanced cheating methods to get the highest rating though, because you'd match the engine too much and be banned.  You could only do it to boost your rating.

Good old cheats best free coaches in the world.

Speaking of cheating, I ran into five players in a row on lichess that played the exact engine moves for almost the entire game. Maybe I'm just bad, bu their moves seemed very computerlike.