@Riot, Why should marksmen be the only irreplaceable Kog in the Warmachine of a successful comp.
I wrote a post explaining in detail why they are the only irreplaceable role for a successful team composition, and why they currently have no real variation on position (Duo Carry Bot), role (Sustained physical DPS), build (IE, PD/SS,LW,BT, Zerks, Defensive item/TF), and playstyle (Conservative back line squishy).
My question is why they should be necessary, a position I remember a Rioter taking recently.
Right now they are necessary to turn success into victory, while having issues contributing to that success by their own actions - They lack agency, and that makes them unfun to play.
I'm very glad ADC's are getting much more awesome identities and much more enjoyable gameplay, but giving them more power while maintaining their strategic necessity will make them overpowered, and drive non-marksmen out of other positions.
I see nothing to make a Marksmen+Support any less optimal bot lane, while plenty to make ADC's more varied and versatile. With versatility comes viability, viability in places that ADC's have traditionally suffered, and with the strengths of ADC's on PBE I expect them to drive many mids, tops, and jungles away, while maintaining their monopoly on bot lane.
My other post goes into more detail on the current issues with the strategic necessity of ADC's.
On another side note, I really like the direction of your changes. The masteries feel impactful and item choices are real. Shifting away from AS and AD and more towards crit, and increasing the AP ratio against towers is good for helping lower the advantage marksmen for taking towers, but I don't think it's nearly far enough. At the very least, let hybrid champions deal them damage on a AP AND AD basis, not AP or AD.
with Madred's old uncapped 4% max HP damage would do wonders) would likewise be pretty great.