thought exercise:champion played by exactly one player during a patch cycle. said champion hits 60% winrate. suddenly restricted.
hells at various points things considered not ban worthy, massively underplayed have hit rates that high for the minority who mained them. would repeatedly bone such cases. furthermore abusable.
skarner is 97.25% Role Rate jungle pick. 55%+average winrate after a sample of 6626 games(5.16 cycle, champion.gg data). whats his overall when people choose him other places as well. for that matter how hard is it to smurf tank with said champion to lower the overall winrate? if the statistical sample is only hitting in the 4k games range for some champions by patch end thats a fair bit of time to get a statistically significant number of failures in, and some quadrants of the community are in fact the sort who would do so. just look at feedlfg for example of such extreme behaviour patterns in pursuit of basic ip gain, and their average game length targets ~7 minutes per.
such a system would need to be somewhat more intelligently designed to have a hope in hell of working or it would only help in the case of high pickrate high winrate all position champions, and would still need to delay until pickrate was high enough to not be able to skew the samples in a given unit time, or clamp far too early(ie with no wait time or lead time it would decide disable champ after two games played, two wins. clearly undesirable behaviour of such a system, so finding a safe/good/effective lead in sample count would be very very very important).