Growth Coefficient on ADC is the biggest restriction
Yorick/Mordekaiser/Illaio/Darius: +5 AD Per level (Level 18: 140-145)
Miss Fortune: +1 AD P/LVL (Level 18: 63 BASE)
All ADC (except jhin for a nonsensical reason): +2 AD P/LVL or at least Sub 3 AD/P LVL
Why is this an issue? We live in a MetA where ADC could literally be 3 items ahead and lose to a 2 item tank under almost all circumstances. The exceptions to this rule are Twitch and Vayne, where stealth has directly increased their viability in this Meta.
The issue lies at base numbers. Why Soraka has a growth stat of +3 AD/P LVL and MF can have +1 is disgusting.
**TL;DR: The base stat growth is imbalanced at its core. The disparity is huge, and regardless what items are implemented, mobility creep and base stat values will dictate that someone else will always do it better, unless you are in the Vayne/Twitch Category. **
and
or tank items like
if their base ad growth was increased.