Early/mid game, their damage is CURRENTLY laughable. But late game, the still have the damage to solo carry like in adc meta... not too long ago. The only reason it doesn't feel that way is because you almost never GET to that point in the game. If you do... you go back from the taric+yi funnel strat to the... (insert any crit adc here - ex:) caitlyn+friends strat. You know the one where mages can't solo kill anyone unless they're 10/0/0 and 2 levels ahead of anyone else in the game... the one where bruisers can't be played... just cc tanks to engage or peel for adc because everyone else dies to adc in 2 sec or less.
Some people like me asked for adc SCALING to be nerfed. So that they wouldn't be the only viable late game carry option. And that in turn adc's be made more competitive with their peers mid/early if they're scaling adc's. So their power curve would look more like... moderate-to-slightyly weaker than other roles early, slightly weaker mid, moderately stronger late (only slightly or not at all compared to other hyperscaling stuff - like fiora for example).
But if that's not going to be done... you can't just buff such a hyperscaling champ's early game and not shave off their power advantage late in an equal proportion.
Also... adc's are not op just because of supports. Nor do all supports offer too much for the gold they have. Some champs offer more with less gold, but also don't scale as well off gold as other champs do because they are less item dependent. Two easy non-support examples would be mundo and rumble. Neither needs a ton of gold to be strong.
engage 
defensive 
assassin???
) still offer far too much value for how few resources are put into them and are all, without exception, broken by design. Yet for some reason instead of looking at these champs riot prefers to destroy crit adc.
Champions like 
are pretty much unplayable and deal absolutely laughable amounts of damage. Riot once failed to identify and address the core problem that led to the botlane dominance over the last 2 years.
