That's just not going to work out well. It has a ton of gray area too. Do all supports get utility scaling? How do you decide which characters get it and which don't? How do you decide which characters are supports in the first place? Obviously you have characters designed to support, but nowadays we see people taking champs designed for other roles and playing them as a support, like support Annie, Zyra, Fiddles and wasn't too long ago that we had support Elise.
So if somebody on the LCS starts playing a champ as a support and does well with them, do we then patch them to have utility scaling?
Like, I've seen support Lissandra actually do very well as a babysitter. Do we change Lissandra now to have scaling CC?
Also, not every support can have this implemented on their kit for balance reasons. Like, take Janna for example. Tenacity can't reduce her CC which makes it absolutely incredible to begin with. You really can't increase the time you are knocked up for, or the distance she knocks you back because there's already no counter to it.
It would just be a nightmare balancewise.