I know a lot of people (such as OAM) make a big deal out of this... That somehow the sport, or at least the "premier" bowls, are made worse by the mere existence of lesser bowls.
IMHO bowl proliferation does have some problems (such as the lesser bowls essentially forcing the schools into buying expensive ticket allotments they can't sell enough of to recoup it). And yes, they ARE meaningless to anyone except the fans of the schools invited and to degenerate gamblers.
But I think they were still fun for the fans, and for the players, and IMHO their existence didn't harm the other bowls. Purdue had a middling year in 2018, but they got to go to the chicken bowl in Santa Clara. Given that I'm "local-ish", my wife and I flew up for it, got GREAT seats in the 6th row, and had a blast. It was Dec 27 or 28 or something, so it's not like it was conflicting with the major bowls. And for anyone who had nothing better to do and turned on ESPN that night, it was a back and forth game against Arizona and a wild exciting finish.
IMHO--and I've said this extensively--it's a 12-team CFP sucking all the air out of the room that has made the bowls meaningless... Not bowl proliferation.
I think the "lesser" bowls suffered from multiple issues, even before the current opt out/portal issues. First, we went from NC + 3, to NC +4, to CFP + 4. So that group grew and grew. But I actually think flexing the tie ins hurt it more.
I remember MSU played PSU in the final game in 2008. If MSU won, and OSU subsequently lost to UM, MSU would go to the Rose Bowl, but I was already stoked that MSU was playing in, at worst, the Outback Bowl. Simply playing in a NYD Bowl was a meaningful thing. They wound up losing to Georgia in the Citrus Bowl. But the NC was a pipe dream. Finishing top 3 in the Big Ten, and getting that NYD bowl validation was a legitimate point of pride. Starting in 2014 the Big Ten entered into all of these stupid rules to move teams around. MSU has had 3 great teams since their CFP appearance, 2015, 2017, 2021. 2015 and 2017 qualified for NY6 Bowls. 2017 went to the Holiday Bowl against Washington State based on those weird agreements, even though they won 10 games and finished 3rd. Based on the rules about repeat appearances, if the 2022 MSU team had actually beaten Indiana and gotten to 6-6, they would have been almost guaranteed the Citrus Bowl, because they were the only eligible team that hadn't been there. It wasn't the proliferation of bowls, because mostly those just added more shitty G5 teams, but they made it so the bowls between P5 teams were no longer related to having a great season