It's just extremely tricky to drive, realistically it's the 2nd-3rd fastest car on average over the last season and this season so far.
The distance to P2 is very slim but the distance to P1 is a lot further since the McLaren often has dominant pace to the point of being untouchable even if they mess up a strategy or have a bad stop.
Max benefits heavily from not having to fight a teammate for wins, and the cars around him often fighting with the other P2/P3 team(s).
simple as

The only problem that /agdg/ has is that no one is making a good game.