So i'm just gonna copy paste a previous comment that I've made about support items ...
''I think that the real problem was how badly non-support champs could easily abuse the items.
Frostfang provides a 20 AP and 10% CDR which is almost the same as Fiendish Codex for cheaper. The active movespeed on hit AND self generating gold was what made this item so appreciated by non supports. As a result, they could snowball easier and there were basically non drawbacks of buying that item.
Evelynn, Ekko, Vladimir, Azir (blah blah blah) aren't supposed to buy frostfang, yet they still do.
Targon was so problematic that it was the standard starting item for Bot lane. Adc's who would take doran's blade were struggling against targon users.
Most of the time, the support would also take Targon which would basically double the income for the support and provide a very reliable healing for the adc. Enchanters such as Sona and Lulu would see their poke become completely useless considering how much hp they would gain back.
The biggest problem was how big the passive shield was during mid game. As an adc, you should NOT be tanky which wasn't the case. Heavy carries such as Vayne, Kog maw and Tristana would see their win-rate skyrocket since they have a relatively easy laning phase.
Nomad Medallion is mainly abused by top laners (especially Nasus). Taking that support item helps you get less penalized when you miss loads of cs. On top of giving back mana, it would ease top ganks because of the passive bonus movespeed.
It should be clear that support items are meant for the support role only. Thus, moving the sighstone INSIDE a support item gives to most carry champions an unwanted stats which would greatly discourage them to buy that item.
I can see certain champions who would still abuse of that item such as Lee Sin, Karma, Morgana. But it certainly would not give them a power spike like the previous support items''