Magnus lost a game a few years ago to a player barely in the 2300's, so highest rated GM is highly irrelevant.
Yeah, Carlsen misplayed that one, for sure.
Though, the player who beat him (Vokhidov) was the 2015 World Champion (U14), and he's now a Grandmaster closing in on 2600.
I think it's fair to say that Vok was underrated. (Although I believe he was 2450+ at the time.)
I don't care about any "system" since they are full of biases. I only care about how many moves match the top moves of the engine. Old masters are just bad
That's precisely what CAPS is : Computer Aggregated Precision Score
... and Capablanca ranks in the 2700s according to engine matches.
For someone who seems to know little about the subject, you hold some rather firm opinions.