I think an added difficulty this season is that there aren't any teams that pass the eye test for, "wow, that team is amazing." Whether correct or not, in many years we see teams that just look that much better than everyone else, so top four is ok, because we know that the right one or two teams is in there. This year I think there's little separating the top...ten(?) teams. So if you're looking for the obviously best choices to play in a single-elimination format, it's less obvious who those are. It's not totally unlike that LSU championship way back in whenever when LSU sort of fell into the championship game because other teams kept losing.
Clemson seemed like an obvious choice (but not a truly dominant team--it lost to Syracuse, and not 1996 Donovan McNabb Syracuse, but 4-8 2017 Syracuse). Did any of the others? Trying to get rid of duds or question marks on this slate is basically impossible. Georgia got waxed by Auburn, and barely got by a good, but not great, Notre Dame. Otherwise who did Georgia beat in an uncharacteristically weak SEC? Alabama played a schedule as weak as Wisconsin's, and wasn't especially competitive in its loss. Oklahoma lost at home to a slightly above average Iowa State. Ohio State had two losses, including a head scratching beating at the hands of mediocre Iowa. Wisconsin played a schedule as weak as Alabama's, but hasn't won three national titles in the last few years, and lost to Ohio State when it mattered (and as much as I loved this season for Wisconsin, I feel like the Badgers played to their ceiling; could they have beaten Ohio State on a better day--and worse day for OSU--? Absolutely, but I wasn't surprised that they didn't). USC, the PAC-10 Champs? Notre Dame destroyed them (and they lost to a decent, but completely unhelmety and otherwise Iowa-y Wazzu). Penn State would have had an argument if it had kept to its loss to Ohio State, but the loss at MSU really took the shine off. MSU was probably pretty good, but coming off the year it had last season, the uncompetitive loss to ND, and a week after losing to unhelmety Northwestern, that was going to leave a mark.
This was an unusually parity-ish season, I think, with no one really standing out and making discerning the proper four teams harder than usual.
So while I think I would go for an eight-team playoff, which would have been better this year at capturing the contenders, in a season of mediocre champs, are the last three in Wisconsin, Miami, and USC? Do Penn State, UCF, and Auburn all have legitimate beefs that they were just as above average as those three (or any one of those three)? What about TCU (it's not our fault we had to play Oklahoma twice!)?
So while my comment earlier was basically a drive by answering the original post, it gets to the heart of it, which is that the single-elimination tournament is a bad way of crowning the season's best anyway you look at it, and when you start looking for different ways to cut this, there is so much subjectivity in a 120-team field that only has a 12 or 13-game season, that years like this one, where no one really looks that great, make it harder.
So no, CFB isn't especially good at crowning a season's champ, but this season wasn't particularly good at providing obvious options.