hmm... Interesting, as another main support, I can't say that I disagree with you. I get frustrated by bad adc's, but usually because they are flaming me for... well, nothing really. I healed them, I zoned, I shielded, I warded, I pinged, and they still chose to chase the enemy and die, avoiding non of the skill shots, ignoring the damage difference, running when I stun or exhaust them, then going in when they recover. Yeah, I could go on, but as I said, i don't think you're wrong. Getting upset or flaming back has NEVER helped me. I might mute them, because at the end of the day, their toxicity is only making me play worse. If I just keep going, keep trying, even if it means they die but I protect the turret and avoid giving away double kills. And when I roam mid (or very rarely top - more mid to late game if I am lulu or bard) and we get double kill and save a tower, I know that I can synergise with other players, and I am not the one failing. If I am patient and use my skills where they ARE utilised, you can come back from a losing game, and when the adc DOES finish their 3rd item and starts actually getting kills and saying gg and wp instead of useless and ff@20, I know that being patient with them and focussing on the game and doing my best is the ONLY thing that works.
it's also I reason I like champs like Taric, he can zone well, be a nightmare 1v2 under the turret if the adc dies or starts flaming at the nexus while you are solo defending. He can even use his stun and heals to deny farm (the cannon minions at least)
I don't think you can completely "compensate" for a bad adc, if they don't know how to last hit, if they can't position themselves or move out of the way of skill shots, you have limited options. I remember being flamed consistently for letting Blitz grab me, my adc did not even see that I only get grabbed because I dived in front of them when blitz went for the hook. Body blocking skill shots, even using flash to stop them from getting blitz'd (I mean that literally and with the pun). Supports have the hardest time, not because ADC's are bad, I've played with bad adc's and had fun. It's hard because the adc's blame the supports, and THEY start flaming when THEY are the ones failing. I just wanted to emphasise that point. Yes, flaming them back is wrong, yes, you are meant to help them make up for their "weaknesses" but at the same time, ranting on these forums helps you feel better because you have been putting up with those that are just "bad" pure and simple (there is a difference between "bad" and "Weakness" not being able to farm at all, isn't the same as not having good range)
One final point, I have reached a point where you can assist farm. Usually when under turret, the adc doesn't realise they have to shoot the minions "before" the turret does, so they can land the last hit. So I have to hit the minions the adc is ignoring, so that the adc can land the last hit once the turret weakens it to kill range. But even then you will often get pings to stop hitting minions, even if you're literally feeding these minions to the adc with a spoon. (again, this is rare, most adc's know how to farm if they are not under pressure, but as main support stuck in silver, I still often see adcs that can't even farm when the enemy is at base or just died and they have all the time in the world to last hit, but miss 5 in a row because they lack the timing)
Oh, and when I say "stuck in silver" I don't mean I am Plat or deserve challenger or any of that crap, just that as a main support it's hard to influence the game, last season I went main mid and got Gold easy, but cause so many people hate support and it was my second main, I just mainly go support instead and yeah. If i'm the worst player, I get carried, but if I'm the best player, it doesn't matter, its almost impossible for a support to carry, whether it's a utlity tank leona, or an Vel koz with 80k dmg a lose is a lose :/
u will never hear me complain
:P