Support mages, Ziggs and Caitlyn are't used because they're too strong

They are used because actual supports suck badly. Non-support champions sucessfully played as supports:

Why? Because these offer more than actual supports. Naut, Annie, Veigar and Trundle are/were used for their utility (reliable hard CC mostly), Velkoz, Brand, Zyra for their carry potential.

Guess why are so popular? Because they are SAFE. They can farm from long range, have some mobility/safety and can peel for themselves.

Supports can't peel as well as , can't match poke/kill pressure of .

As far protecting goes, well-placed CC is often better than shielding/absorbs, which is why were Annie, Trundle and Veigar valueable - reliable point and click CC.

These are FACTS. Now for speculations.

We know certain supports sit at 52-54% win rate, which may indicate they are VERY STRONG picks. However, this is inconsistent with fact that they are pushed out of support position. If they were strong, they wouldn't be outclassed, right?

Supports are designed to function with low income and xp. On the other hand, mages require tons of gold and xp to work well. If class that needs gold/xp to work preforms as well or even better in position with low income than class designed to work there, something is obviously broken.

Question are: Why are win rates of certain supports so inflated despite them preforming rather badly?

Why have actual supports weaker utility than non-supports?