Just 15 schools have won a national championship since it became a lot harder to win one, when college football started trying to determine a national championship on the field. Before that, all a team had to do was have a one-loss season, win one post season game and place first in one of a half-dozen polls to claim one.
Which, coincidentally, is exactly the standard Oregon met in 2024. They went undefeated in the regular season, won a postseason game against a Top Ten team, and finished No. 1 in the Wolfe and Hester computer rankings.