Riot thinks ADCs should be building crit, so some items should be melee
We can see this from the more recent changes to champion kits to favor critical hit builds-- MF, Jhin, etc. And the decrease in crit item costs, as well as the change to Bloodlust.
Now, items like Black Cleaver and Youmuu's, which are intended for fighters and assassins respectively, should righfully be made melee-only. ADCs who want more cooldown reduction should be buying Essence Reaver to coincide with the rest of the build.
And any ADC who would lose lane strength due to this would be adjusted accordingly-- especially since the two that would have a lot of crit interaction in their kits besides the AA damage and so should rightfully be building it anyway.
and
want the black cleaver