Incorrect. It means that base stats and the scaling of them more impactful not just adc's but everyonel.
this means nerf damage across the board buffs everyones defenses. so level 5. It just means that Rammus is a bit more tankier. It means at level 7, perhaps that LB cannot one shot your bard who is level 5. Perhaps late game that means Galio could be tankier against a draven than a Pink Ward would be.
So if everyone is tankier. it means Adc Have a clear goal of actually dealing consistent damage.
rather just letting a AOE like mage to one shot entire teams. Like
and
they would deal less to entire teams, and cannot get a job done like an adc could.
Because if you buff adc defense stats they'll just go top and can reliably tower dive or become draintanks. They'll just become a lane bully early and a late game monsters.
Or thats how I see it.
And buffing damage, only makes them more 1-shot glass cannons with large targets to be one shotted.