I don't think you realize how popular the Chili Peppers were in the 90s. They were already playing stadiums, headlining festivals, and very much a part of the mainstream. I would say it's their 90s-era stuff that's the equivalent of The Wall, their 00s stuff is the equivalent of Momentary Lapse of Reason. Sure their 00s stuff sold well, just like Pink Floyd's 80s stuff sold well, but that's not because they were breaking into the mainstream, it's because they were already a long established mainstream act at that point.