Separate from any practical considerations, you could make a formal argument why WTA works better. The current approach does pairwise comparison, that means it only considers a playerās ability to beat opponents. But that is a bad proxy variable for winning games in FFA. As we can show with an example, where we imagine games of players of all exactly equal strength (to keep it simple).
Using the binomial theorem we can obtain the probability to finish in a certain place with the following equation for these games, when making use of pairwise comparison:
f(k,n) = n! / (k! * (n-k)!) * 0.5^n
, where: n is the number of opponents (i.e., n+1 is the number of players), k is the numbers of opponents beaten (i.e., n+1 - k is your placement after a game) and f is the probability to beat a certain number of opponents (i.e., to finish in a certain place).
From this equation it follows that the approach of pairwise comparison inherently underestimates the probability for a player to finish first or last in a FFA game. Letās take a 6 player game as an example. Of course 1 player will finish first and thus beat 5 of their opponents. Since all players are of exactly equal strength the chance that this happens is 1/6, which we can also write as 16/96. Pairwise comparison, however, predicts that itās fairly unlikely to beat 5 opponents for any of the players, since if they were to play 5 1v1 games each, itās much more likely to win some and lose some than to have a clean sweep against opponents of equal strength. Thus, using the equation above, we can find that the pairwise approach predicts a chance of 1/32 or 3/96 to finish first (or last) for any of the players. Which is a serious underestimation of the actual chance of 16/96. From which we can conclude that although winning a FFA game constitutes beating your opponents, only considering beating opponents is a bad proxy for winning games in this context.