I never understood the pomposity of both the English and some of the Spanish with regards to weaker leagues and how others build their reputation. What does it achieve? Absolutely fuckall.
A narrative many people like to push. When Bayern Munich lost their finals to Inter and Chelsea everyone said, "the league was weak hence they lost", when they won the treble it was "their league was weak, so they rest players allowing them to win CL.". The same will be said about PSG if they end up winning the CL right now they suck because of the weak league.
History of a club is another thing that gets pushed a lot, history didn't help Madrid from not being KO'ed by Lyon a decade back, history didn't help us from not being KO'ed by Roma, History didn't help United from being KO'ed by Sevilla, History didn't help Rodgers Pool from being KO'ed in the group stages, History didn't help Conte Juve from being KO'ed in group stages, etc.
When you want to win the CL or be the dominate force in CL you need 3 things:
1. Quality players, with a good manager
2. The squad has to have character, experience and most importantly leadership from player or players
3. Luck (self explanatory)
City/PSG have the first one, but lack in the other 2.
Roman/Mou Chelsea is an example despite being a oil club, they had players like Drogba, Lampard, Terry, Cole, Cech, Essien and so forth proper characters and leaders, hence why they were a very difficult opponents. Now compare them to current Chelsea players talented group, but they lack that leadership within a player(s) and character outside of Kante/Hazard.
Looking at City/PSG squad, do you see a Ramos, Puyol, Casillas, Xavi, Chiellini, Maldini, Terry, Vidic, Keane, Drogba, etc. type personality? Pep is basically the leadership at City without him on the touchline they had no one yelling at them and correcting them when they made mistakes or handing out instruction, etc.
It's not just them even us and United lack in this department hence the mockery in CL in recent times.