Late game adc =/= long range adc, it just so happens most popular late game adcs that are popular now have long range. Vayne is a late game adc, but she's not being played due to a hard lane phase (although imo she should be played a bit more but thats besides the point). But guess what? Lucian is effectively Vayne with a godlike dominant lane phase atm and he now hard carries late game due to his ridiculous damage output and mobility. It is most DEFINITELY undeniable that Lucian is the best pick in the game right now. He does literally everything that youd want an adc to do, he stomps lane, he scales hard, he has self peel in his mobility, he has ridiculous damage, he does insane damage late game, he duels crazy well, he teamfights well, he has probably the highest single target damage in the game right now (MAYBE kog slightly beats him here, but Kog doesnt have like twenty 0 mana cost dashes) due to the percentage health damage and double shots he gets, and I could go on.