That's called, "playing the result." The fact that a team loses one game in a blowout doesn't mean they were totally outmatched and had no business being on the field with the other team.
When two teams have been playing at high levels without experiencing much adversity, sometimes it doesn't take much for one team to shatter the mental confidence of the other, resulting in a blowout despite the teams being evenly matched on talent.
After the 1996 season we beat FSU to win the Natty in a 52-20 blowout that wasn't even as close as the score indicated. It's hard to argue that FSU had no business being on the field with us, considering that they beat us just over a month earlier.
"Playing the result" is the same thing that people do when they argue that there's no need to expand the playoffs because there are never more than two truly "championship-caliber" teams in the first place. Yeah, that's the point!
The purpose of expanding beyond four teams is to break the cycle of only a handful of perennial top teams -- namely, Alabama, Clemson, tOSU and OU -- stockpiling the top talent and appearing in the CFP year in and year out.