This is true, but the more teams you allow into a playoff, the less deserving each additional team is. Socially, as a culture, we should be inclusive. But when determining a champion of a sport, we should be exclusive. If you don't win the beauty contest, keep knocking at the door or kick it in and eventually make them see you by winning.
Take UCF. We have learned that a UCF team with 13 straight wins isn't allowed in. We've learned a UCF team with 25 straight wins isn't allowed in. But at some point (whether it's 38 or 50 or 100), they will be let in. I guess it's not fair that a Notre Dame can get in after "only" 12 straight wins, but that's life. If those UCF players could've gotten a scholarship from ND, they'd be playing for ND. This is competition, dog-eat-dog, from recruiting to facilities to games on the field and to the rankings. What should UCF do? Keep winning. Win until you get in.
Why is 8 the right number? Why not 16? Why not 6? It's so arbitrary. It'd be random if cubed numbers didn't exist, which is hilarious, actually. And if 8/130 teams (6%) is the right number, then why does every single other sport have way more than that in their playoffs (NFL 37.5%, NBA 53%, MLB 31%)??? If the best answer to that is "because it's more than 4", then that's embarrassing.
To the first paragraph, that's fine. We want less competition, that's OK. We can just say it. The goal is making the season a pageant when number of losses rules the day, that's AOK.
To the second. In the current system, USC will never get in. Could win 100 and it won't be let in because each batch of 12 will be found wanting. Maybe the stars align once, but for the most part, they'll be out. And whenever they lose, someone will be here to say, "If they'd only done it once more, maybe it coulda happened."
I dunno if eight is the right number, but it's the next one that allows for a clean bracket. I don't know if it's right or wrong. I know the current system is 3 percent, but that's really 6 percent since half of FBS isn't eligible. At the moment, there are five power conferences, often one G5 team that wins all its games and usually 1-2 teams where we ask the last week of the season about "They have two losses, but are they one of the BEST teams" because of that stupid wording. So at the moment, eight seems pretty clean.