Just Because You Found Some New Meta Bot That Works...
Does not mean it's viable.
Sure, it'll be good but ONLY because people are not expecting nor used to seeing that pick bottom. Also, 5 or 6 games to "prove" your champion is busted in bot doesn't really make me convinced.
Most of the time it's gonna be a melee character. Melee characters are easy to focus. Therefore not viable in bottom. Obviously this does not necessarily count for champions like Gangplank or Jayce since they have ranged abilities.
ADC's are also far superior in late game, so they are there IF late game should happen. Which it does, even in this season.
ADC's can also kite and they can burst down tanks, very few other champions can do that in the game. Even with the armor penetration.