Your support is not your mother, they are your LANING PARTNER
So far as I can tell supports exist for two reasons:
- we have 3 lanes, 1 jungle, and 5 laners per team
- adc's require the full minion gold of a lane, but are (usually) vulnerable without a partner
As a support, literally the extent of your actual responsibility is not taking farm from the adc, and making it harder for the enemy team to kill them (I'm not gonna get into sightstone, that's irrelevant to the point I want to make). Playing a character who is skilled at getting the carry fed is one way to contribute to the team, but it is not the ONLY way to play support.
So, if I pick a mage that can help keep you alive, you should have no complaints. I'm not your sidekick, I'm your partner. The cs is all yours, I'm not disputing that, but if I can take kills and give value to the team by snowballing and providing damage WHILE ALSO PERFORMING MY BASIC DUTIES AS A SUPPORT, then I will and you have no moral high ground to get haughty with me.
For example, if I play Vel'koz support, I have a powerful multitarget slow on my q, and an aoe knockback on my e so I can generally keep you alive unless you do something stupid. Unless you failed to notice what I picked in champ select, you should KNOW that I'm not playing lulu or tahm kench, and if you flash into their minion wave, then you will die, and it is YOUR fault. In addition, any kills in the lane are fair game for EITHER OF US. If I can make use of the kills and profit the team in taking them, there is no reason for me not to, and just because you are promised all the minions in the lane does not mean that I can't farm champions. And it CERTAINLY doesn't mean I should need to bend over backwards to force feed you kills that I can more easily secure myself, nor that I should refrain from attacking low health targets at all with more fear for stealing kills than letting them escape.
Tl;dr: any champion is a fine support if they can reasonably keep the adc out of trouble, and you have no business getting angry at supports who do more than baby sit their adc