Almost all adcs scale off attack speed
So won't reducing their base attack speed to a reasonable number make their DPS reasonable after scaling with items into lategame? For example an adc base AS is 0.65, then with 200% bonus attack speed would be 1.95. If they hit 500 per auto average, then their dps would be 975. Now if we just adjust the base AS of most adc down to 0.6, then with 200% bonus would be 1.8. With 500 damage per hit, their new dps would be 900. That is effectively an 8% reduction in AA damage which also reduces the amount they are able to self-sustain allowing more opportunity to counterplay.
Rather than playing around with multiple variables from items and other classes, wouldn't it be easier to adjust a single variable until balance is reached?
<these champions right here heavily rely on AD believe it or not.