You know, I was expecting to hate this post, but no I actually completely agree with OP.
I'm a support main too, and being a support main sucks. You're basically forfeiting your ability to make meaningful contributions to your team on your own. Support is an enhancement role- that's why it's called SUPPORT. If your team is bad, you as the support are helpless. Putting a good support on a bad team is like pouring a really nice mushroom sauce over a charred-black steak that was made from half-rotten meat- the sauce may be nice, but you're still gonna end up with a bad case of the shits.
Support is an essential role that needs to be filled, but it's a thankless job where you're gambling your victory defeat not on your own skills, but on those of your teammates. Sure, this is something inherent to EVERY game of LoL, but the fundamental difference is that a support cannot carry, at least not by playing as a support. Anyone who tells you otherwise is a god-damned liar. If your team is bad, you can do all the perfect warding, peeling, initiating etc you want, they're still going to fuck up and waste your efforts and because you don't do large amounts of solo DAMAGE you can't carry. Supports do not make solo plays- they set up plays for their team, and if their team is shit they're helpless.
The closest you can get to a "carry support" is picking something like Karma or Brand, realising that your ADC is a brainless trash noob who you're wasting your efforts on, and just start taking all the CS for yourself so you can build enough damage to carry in their place. This is technically bad support play (and will probably drive your noob ADC to afk), so it should be an act of last resort.
Seriously, I love playing support. It's my best role and it fits my personal style perfectly. But when you get stuck supporting someone so bad they literally shouldn't even be allowed to play, you know true agony. The only reason I keep playing support anyway is because the sheer number of "supports" who pick Lux or Malphite then build straight AP or tank without even pretending they're actually a motherfucking support and not a 0-CS mid/top-laner makes me physically sick. You know what they say, if you want something done right...