Well, it's a lot more complicated than that, isn't it? You're forgetting all the context involved with match-ups and possibly dialogue exchanged. I for one hate ADC because my performance is tied to my support, and the same in reverse. There are some things I'd like to point out though...
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It's only okay for a support to take a kill if it's to secure it. By definition you're the support, and you're not going to snowball off Support Sona and carry your team, unless the enemy is bad. You do little to no damage, and really only your cool downs and items will change from getting the gold from kills. It's far more efficient for the ADC to get the kill, then snowball the lane. And trust me when I say this, I've seen a really big rise in greedy supports who want kills.
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Warding is one of the Support's main priorities. Sure if you're ADC and your ward is off cool down, drop it somewhere. But pre-9 they won't be able to help with vision, and the trinket cool down is pretty bad. You're the support, learn to ward correctly and when to ward. I've seen a lot of supports think that warding the river was worth taking a Morgana Q or a Blitz Pull. You can argue Wards are free all day. Doesn't change the fact that pre 9 they only last 60 seconds on a 120 second cool down.
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You don't have to be a tank to engage, let's get that cleared up. In a laning situation (2v2) it's the support's job to initiate fights. Either by landing a lot of harass and opening up the situation of a skirmish (Sona, Lulu, Karma, Zilean, Soraka), by hard engaging with the intention of tanking (Leona, Thresh, Alistar, Braum, Blitz), or by landing a CC to incapacitate the enemy ADC (Morgana, Janna, Bard, Nami, Zyra, Lux, Fiddlesticks.) Outside of the laning phase, you can still do this and watch for enemy positioning. A Good Support doesn't have to be a tank to initiate an amazing team fight.
With that said, yes, supports get tons of shit. But that doesn't mean every complaint is just rage and misplaced anger. I've had a lot of supports refuse to get a sight stone, reducing our visibility well into the game, until I upgrade my trinket.
Also seen a lot of supports so scared to do their job, they forgot to harass, heal, ward, or even just stay in lane long enough for them to get Gold passive off my farm, last hitting cannon minions, or harassing.
Support's aren't perfect, and you should never rage at anyone in general. But again, this doesn't mean it wasn't justified.
- Sincerely, someone who has to fill support a lot