So, I've been thinking, and it has come to my attention that Swain would be an awesome ADC. Just think about. A bunch of CC, a healing ult, an E that makes him deal increased damage, and a passive that makes him extremely sustainable in lane. So why not Swain ADC?
the single reason to have an adc in the game is that you have very high physical ranged damage that can siege towers and a way to split damage dealers across the battlefield so your army is less vulnerable to AoE. tho this can be mitigated and if it wasnt for sieging towers, there would be no marksmen champions used in the game except maybe corki because hes just so good at skirmishing early to midgame.
marksmen have a rather weak laning that cannot withstand bruisers, so they have a support to help them get through laning to be high damage later. if you want strong laning, you can play anything. like, you can play AP swain botlane who cares. but if you want high AD damage, why would you play swain? he has basically no damage steroids like most marksmen have.
you can play every mage on AD, like marksman-leblanc is decent sure. marksman-ahri too. they both have good mobility and cc to have decent early to midgames even if played on AD, but both of them have mediocre tower-killing-power and dont scale on AD items because they have no steroids.
keep in mind that most champions can do many things but its not very optimal, so depending on what you want to bring to the team, pick your champions accordingly.
