Obsolete supports. Why don't use always a midlaner or adc as support?

Hi, I think the support figure is a bit obsolete in "normal" (non LCS) games. It's too sad too see how, let say a Janna, which was a good support in the past, out scaled by almost every single champion, by utility, damage, cooldowns and tankiness. Compare Janna vs Bard/Thresh/Brand/Karma/etc etc. Bardo has a low CD and high damage stun/slow, disable (disabling a couple of people around 3 seconds, win team fights), tunnels and heals. Janna has a slow, a knockup (hard to charge), shield, and knockback/heal, but she has tons of mana problems, she deals almost zero damage after level 4, and she is ultra squishy. Another example: Alistar. Cooldowns of 20 seconds, still he has mana problems. Useless healings after level 3, deals low damage and can be poked. Compare it with Braum, Thresh or Nami... or even Bardo again

Anyway this can go further. Lately I'm seeing a lot of strange supports. Like Miss Fortune, or Lee Sin, or Ashe... all of them work better generally than the classic support figure.

Of course, I've adapted to this new tendency and I'm using such strange supports and enjoying generally better results (went from Plat 2 to Diamond 3). Tip: ban soraka, then poke, poke and poke. Easy. But, I write this because I miss those days where the support had a place in League of Legends, now it has been replaced by a secondary mid laner.