This. Until Nico retired, Merc was as dominant in the W/L column as RBR is now. In the first 3 years of this PU era, of 59 races they lost a total of 8 races. 86% win rate, but there was a battle within the team, so many people didn't care.
Since the start of 2022, RBR has lost 6 of 45 races, with the same 86% win rate.
After Nico retired (and in large part imho because Nico retired & was replaced by 'excellent wingman' Bottas), Merc wasn't as dominant. But Lewis winning the WDC was more of a foregone conclusion than when Nico was fighting him. Bottas was no match for Lewis and was never intended to be one. In 2017 & 2018 (the 4th & 5th years of the PU era), Ferrari was finally able to put up a fight, but in the end they didn't really get very close, and never would have had any hope with a better driver (such as Nico) in the Merc #2 seat.
The funny thing though is that despite all of Perez's mistakes, in the dominant years of each car, Perez has scored about the same points per race as Bottas. He's finished P2 and a close P3 (by 3 points). Bottas finished P3 and P5 his first 2 years at Merc. They're also not far off in terms of race wins in the WCC years. Bottas 10 in 5 years, and Perez 4 in 2 years.