- Is it the surrounding champions in the other lanes that dictate the sucess of Lee Sin and friends?
A lot of it could just do with perception now.
Perception plays a pretty massive roll in performance. If a lot of people think champion X is solid, a lot of people might master champion X. If that champion is seen in competitive play that an continue well into the future.
Unless Riot nerfs a champion so heavily they're completely useless it takes a really long time for people to stop playing them.
Lee Sin and friend's win rates are actually pretty terrible ATM. In profesional play they aren't the most impressive performances.
Currently Lee Sin is sitting at the 14th worst monthly win-rate overall according to LoL King.
Elise, Rengar, and Evelynn are also in the bottom 15 win-rates. At least when I posted this.
Sometimes LoL King just sends people to "charts" rather than "Monthly lowest win rate charts", sorry if that happens with the link above.
Also - Lee Sin, from everything I've heard from my friends that play him, is extremely fun to play. Pretty much everyone that plays him reasonably well loves the guy, so he's bound to be a popular champion just because of that.
Given his current win rate/performance in normals, ranked, and worlds - I'm not sure I'd call him dominant in any aspect beyond popularity though.