Remember, I think it was a couple or few years ago, was believe it was for a Snowdown we had a 1v1 and a 2v2 game mode on Howling Abyss map. Was first blood on 1v1 and first to 2 kills on the 2v2 (I think) and you could back to regen and buy. I miss that mode...
It's now called invite 1 person or 3 people and create a custom game and have at it. Nobody cares how good someone is at 1v1 or 2v2 in a team based game except the people who think others care so why should Riot waste resources creating a mode that most could care less about. You have the ability with custom games. That is enough.
It's nice to dream about but as a concept it's inherently flawed. Unless you put very specific restrictions in place, it's just going to devolve into a contest of who has the safest and most punishing early game laning power in a vacuum.
The answer is cait. It's always been cait, every time this mode has come back. If not cait specifically because of bans or draft or whatever, people will pick the next best thing which will be another adc. Adc's auto win 1v1 lanes in a vacuum against non adc's, and in a contest of adc whoever has the strongest lane phase wins.
If they made a mode where you picked one of the roles (marksman, fighter, mage, assassin) and then it was always a duel between the same roles, or even if they just matched it up so everyone was in a mirror match, that would at least bring the mode closer to the idea of skillful 1v1s between mains of various champions like you imagine when you think '1v1 map'.
Otherwise it's just going to be cait or whoever is closest to her in laning strength all day.
