B+ for going 0/0/11 as a support (Zilean)

When crafting comes out and people are rewarded with loot for getting an S, what is my motivation for playing support when Riot doesn't think doing my job as a support is important?

Edit: Here's the game that was support Zilean http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2097337797/203781211?tab=overview

Here's the match I played immediately after as Cass which I got an S+ http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2097410673/203781211?tab=overview

I feel like for both games I played my ass off and performed at a high standard. It just seems like Riot rewards better ranks to playes with kills. I get S on Bard quite often because his meeps were buffed to the point that with I can often kills on squishies.

I'm just highlighting this example for Riot to see so hopefully they'll reevaluate what the grading system for supports. FOR EXAMPLE, BEING MORE FORGIVING FOR RANKS AS SUPPORT WOULD ENCOURAGE MORE PEOPLE TO PUT IN THE SUPPORT ROLE FOR DYNAMIC QUE, WHICH MANY PEOPLE HAVE BEEN COMPLAINING ABOUT. Or you could give supports smaller amounts of loot for A ranks or something

Edit #2: Here's another game with support Zilean where I DID get an S- (I got 3/2/19) http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2097722742/203781211?tab=overview

A lot of people are commenting how the grade is relative to other Zilean players, and that other Zileans have a much higher KDA ratio, thus I should be deserving of a lower grade because 11 assists out of 17 total team kills is only a 65% kill participation, thus justifying my B+ grade. But in my next Zil support game, I participated in 22 out of the 31 kills, which is a 71% kill participation. A mere 6% bump is jump in 2 grades. I credit this jump more to the fact that I had 3 kills rather than a slightly higher KDA, further cementing my argument that kills are worth too much in the grading system

People are also mentioning other things that effect grades, such as wards and objectives to name a few. Let me get this out of the way. As a support, you are very much dependent on your team to land objectives. You could play your freaking heart out as Zilean and still see little results if your team doesn't have the brain power to use their ocular devices when you have Chronoshift on them. As for wards, shouldn't this be a team aspect? I put down 8 less wards in my first game because the game was 20 minutes compared to 25 minutes. What I'm saying here is that while Riot DOES factor these into the equation, but it'sblantaly obvious that kills are worth WAY more to your grade than they should be