Original point: Some supports are very strong relative to their difficulty of use.
Thread becomes: Blitz damage isn't the number you said STFU scrub
Not that the original point is necessarily a good one, at least for someone in low silver. Speaking as a support main around that level, passive supports like Janna and Soraka are trash tier if their team falls behind, and in low elo most players don't know how to make use of having such a pure support champ on their team. Blitz is Blitz; if you can play around him, or if you get a chance to pick counter champs into him (Ezreal/Rakan/Morgana), his usefulness drops dramatically because you'd almost always rather have a good Alistair as a tank in a teamfight. Thresh and Lulu take more practice to use well, and apart from her polymorph (which is a big deal) Lulu broadly deals with the same team-based issue as Janna and Soraka.
I used to ban Thresh because even though Blitz hooks are more dangerous, Thresh's kit is harder to fully dodge. Now I ban Lux, because the double root is a huge problem in high bronze/low silver solo queue and, more generally, I see hard mage supports all the time now (or tanks, which are much easier to deal with while laning). Mages are far more useful at silly-bugger level than the ones high elo and pro level players make good use of.
I see the OP normally plays mid; if you find Janna and Soraka are becoming problems when you're not in their lane, roam more and gank them so they fall behind. If you get an ADC game, don't let them get started—don't get ganked and call for your own. Their weakness is that you don't really have to beat them, you just have to not get beat by them. They get much easier to handle once you find ways to do that.