Best players of all top clubs don't start every game, that's completely normal especially when you have games every three, four days. Messi, Ronaldo, Mbappe, Aguero, KDB, Salah and others started some league and CL games from the bench.
Not saying Mount is in that category of course. But him being dropped against strongest opponents (City and Liverpool in Super Cup) and in most important CL games make it look even worse. Basically massage Lamps is sending is that he don't trust Mount to play when we face best clubs and when we have most important games where we must take the result. I bet he won't start against Bayern either. I see hypocrisy there.