Well, it's easier to win CL with Real Madrid, in comparison to any other club.
With or without Mbappe, Madrid is already a feared team in Europe, and the most successful and consistent one. And they're not depending on a player or a manager to keep their level at the top.
Curiously, I am yet to see an article in Catalan press to address why is that exactly.
Maybe it's just so plain to see but the topic is avoided like a plague.