I can remember proposals for (lower case) college football playoff schemes for literally decades. I have a copy of Death to the BCS on my bookshelf; it has a proposed 16-team playoff bracket on the back of the dust jacket. Published in 2010, it’s one of the more recent polemics on the topic.
I used to be in favor of a playoff of maybe six or eight, but I have since changed my mind. I think four is the correct number. Because I saw perhaps more talk of an eight-team playoff this year than any others in the College Football Playoff era, I feel the need to explain why.