Utility scaling is taking too much power budget
Bard has no utility scaling. That could be a sign that it did more harm then good on other supports. Let's see:
Lulu went to terrorize mid and top lane with her new scalings. That lead to several nerfs, including the removal of utility scaling on her Q. Riot has not lifted a finger to help support Lulu after those nerfs.
When Nami builds AP, she gets more movespeed on ability cast and a stronger heal. In patch 4.13 Riot preemptively nerfed her before she became too strong. They lowered her base movement speed and raised the cooldown on her heal. Exactly the places she got utility scaling.
The queen of peeling scales so well with AP, that she frequently buys a Mejais. The counterplay: kill one of the safest champions in the game. It also encourages Janna to stay passively in the back instead of sacrificing herself if necessary.
Sona is really scary with a Lichbane and a Deathcap. To keep her from becoming oppressive, she has been nerfed repeatedly. Is damage when she gets to build AP really where Sona's strength should be?
Soraka can't build tanky because of the % max health cost on her W. AP is actually a decent alternative that makes her better at healing, so I think utility scaling fits on her.
Everyone with utility scaling can potentially have huge power if they are building AP. A big part of that power is damage. I would rather see that supports became better at their core job: supporting. Are we ready to admit that utility scaling did not work out as intended?
's main form of scaling is via his chimes and meeps, so he's like
in the sense that he already has a means of making his support contributions scale, and doesn't really need additional utility ratios. There's also very little in his kit that could be made to scale: bar the movement speed bonuses on his W and E, it's not really possible to add a ratio to his other forms of utility (the slow on his Q gets overridden by its stun, so it wouldn't do well with an AP ratio).
and
are pretty much mandatory on every support build, and coupled with the fact that supports still have the lowest gold income on their team, they can't really display the full power of their utility scalings.
for example got to bot lane because she has a permanent and always reliable stun to back up with extreme offensive power, but lacks every single othe tool that supports bring on the table in forms of utility(heals, slows, silences, shields, disengage/engage and whatnot). Why pick