high mobillity, pure damage no utillity, mix of burst and dps, most of his output is pretty reliable, so yea, where is not much specific he offers for a team, so whenever he is good enough to be played, he is so because he just deals a shit load of damage for his mobillity.
Also, mobillity, solokill potential and overall high damage is always a combination that makes for a very high playrate even if he's not that insane powerwise if atleast decently strong.
Also adc in generall, there is still not so much difference between them, so usually the ~3-4 best adc share 90% of the playrate cause there is little to no reason to pick anyone else on that position.
There's prettymuch always atleast one adc with 30%+ pickrate...