It's like your arguing over what is the pinnacle of Football - Pinnacle of English Football? Premier League. Pinnacle of European Football? Champions League. Pinnacle of American Football? Super Bowl...
And after you have picked through all that, you still haven't argued over what is the pinnacle of Football...
It isn't set in stone what the pinnacle is, in the same way the career path to reach any level of motorsport is not defined. I don't think many drivers have gone from Formula Renault, to GP2, to Super Formula, to F1. DTM features too, and is Formula E above or below everything else?