I think the blame is on the players more than Riot's flawless coding and their history to be perfect. No one really wants to be be support, everyone wants to be a carry or be able to kill someone by being able to build damage. I mean, I'm a support main (support/fill respectively) and even I get annoyed after playing support about 99% of the time. A lot of hate is usually aimed at the support, if not the jungler, and the rewards are usually less than most roles because a lot of players usually don't notice that supports ARE very important in games, especially at elos below Plat.
And in most cases I've experienced, anything great I did is immediately rewarded to ADCs or anyone else that comes to gank and kill the enemies; rare cases of "great job support" or "op support" because usually it's others getting the kills and supports saving asses or making plays. However, if ADCs fuck up or anyone else, it's usually the support's fault in low elos because we can't seem to accept the fact that we suck and maybe, just maybe, we suck. "gg supp didnt ward river" when ADCs don't even use (sometimes they don't even buy) trinkets to help ward the river around 5mins into the game.
Unless there's a change in rewarding the Support role, we can actually expect those that use the Support or Fill options to be supports almost every game. I'm just throwing numbers over here since I usually read that almost everyone experienced like 10minute queues in non-support roles while I get like 1-5second queues. I think there's like 25 out of 100 players will select ADCs, 25 out of 100 players select Mid, 25 out of 100 players select top, 24 out of 100 players select jungle and 1 out of 100 players select support (ignoring fill because that's usually support). Almost every time I land in champ select lobby, there's 1-2 players complaining about the long queue time if I'm a support. I get 1-5 seconds wait time then I'll have to say I'm ready or be thrown out of queue, not enough time to even go take a piss.
TL;DR I blame players more than Riot for terrible ratio of Non-support to Support roles, forcing anyone who has Fill or Support in either Primary or Secondary roles to be auto locked into a Support role.
[slayer-pantheon-popcorn]