Part of the reason why tank supports are dominating
I've seen this on the comments of another thread and I was thinking.
Nobody wants to be the tank and to protect the carry. Everyone wants to be the carry themselves, especially at lower elos where you can't rely on your team at all to win games. That's why people tend to pick full AD top laners (
), mid lane assassins (
) and damage-oriented junglers (
)
Even when people pick champions that are tanky, those champions tend to be bruisers who are still damage oriented and are lacking in utility, peeling potential, and/or teamfighting presence. Also, many of those champions have balancing issues, and people tend to be attracted by "broken" champions. Examples: top (
) and jungle (
)
Generally people only pick champions who are true tanks when those champions are broken, examples including
, and
at the time that she wasn't nerfed. I am not saying that people don't use tanks, it is just that most of time they want to carry and thus they pick champions who have the most potential to carry by themselves. The problem is that by doing that, they are left with a team that has lots of assassins and damage oriented bruisers. But they are lacking on utility and teamfighting potential, can't initiate teamfights, and are very squishy.
And due to that, people who go support are forced to pick tanks to compensate. People generally don't care about what the support want to do and thus they leave the "dirty work" of tanking and initiating for the supports.
This may partially explain why tank supports are so popular. If people were less selfish and thougth more on their team and less about just themselves, and picked top/mid/junglers with more utility and/or tanking potential, I am very sure that this would allow the supports to pick squishier options.
I am not saying that this is the entire reason why tank supports are dominating. Of course there are other problems; for example, AP supports are lacking on good itemization, and tank supports can usually survive for more time to use their utility. Also, I am not saying that a support can't carry on low elo; but lets be honest, it is a lot harder to carry when you are on a position where you are forced not to farm and you are forced to focus on utility/tankyness instead of damage.
, who deals % HP true damage to herself, and
who needs an AP build to be useful, are seen much less often than
, whose spells are all packed with utility, allowing them to build full tank.
for engage and
But yeah it is mostly tank supports
(and similar burst projectile champs') entire kit with an E XD

mid. If you build him full AP he is of course not going to be a tank. But he can still be very tanky thanks to his ult and Rod of Ages. He is absurdly powerful and bursty, and has a lot of CC.

Why not do both?