It's not that it necessarily shows the better player, but it BETTER shows who's playing best.
There is never a definitive best player, but a longer race better showcases it versus a shorter race.
I agree that a longer race has a better chance of showing who the better player was that day. I have never disagreed with this. What I disagree with is the claim that it always shows who the best player is as many are saying.
My point is and has always been that although the longer races make it more likely you can determine who the best player is (but certainly don't guarantee it will be conclusive), that doesn't help put money in the pocket of the streamer when very few people are buying the long race streams for whatever reasons. And if nobody is buying them, we lose streams altogether. We already lost TAR because it doesn't work. I don't want it to get to where there are no streams left to watch.
And it is likely that some of the people who did not buy long races would in fact buy shorter races because there are a lot of negatives to long races. Long races are usually blow outs that are a bore fest after about 1/3 of the way through the match--no excitement left. Some people don't want to buy something they can't watch all of just like most people wouldn't buy only one quarter of a football game. And there are many other negative issues with long streams as well. Long races have pretty much one good positive (that they better determine who is playing best that day) but a TON of negatives.
So you can have long races that better determine the better player but with little excitement and few people buying them for a variety of reasons. Or you can have medium races with tons of excitement that still do a pretty good job of determining the better player and that don't have all those other negatives that kept many people from buying the long races. Seems like it should be worth a try to me, especially when you consider that we already conclusively know that people just don't want to buy the long race format.
And what may be the best all around for everybody (because EVERYBODY gets what they want) is long matches that consist of a best of several shorter races, like say best of three races to 17, or best of five races to 21. It does as good a job (better actually for several reasons) as a long race in determining who was playing better that day. It keeps the excitement the entire time. It comes with a lot more pressure on the players. Every game always means something. Both players will always be giving 100%. Blowout bore fests are less likely. People that can't watch the whole match may still buy just one of the races because there is a beginning and end to it, and because that race means something.