Realistically I just don't see it working all that well. I think the problem is a lot of players are only skilled at 1 role, or worse just 1 champion. OTP is fine but folks don't like to acknowledge that it can hurt your teammates and your ability to climb.
OTP is honestly the fastest way to get "skilled" at the game and climb ladder.. but your screwed once you hit a range that reflects your skill. A ban or pick can cost ya a match. You get screwed as well if there is a meta shift (if your OTP is Fotm pick or ban good luck. If your OTP hard counter is now popular in meta. Good luck.) hard nerf, and also a rework can completely Fk you and your ability to play the game at the part of the ladder you in.
So you have a risk of matches handicapping teammates and also have a risk of suddenly being grossly outclassed by the players around you. It takes longer but knowing multiple champions makes you a better player because your able to adapt to things in lobby.
Having separate MMR, when so many players already dont have the ability to play all roles at their MMR just lowers the # of active players in higher MMR tiers... Everbody who ques in off roles is placed into lower MMR games. This makes MM have to find a wider range of MMR to build games with. Not really ideal... Riot tried Splashing LP and possibly MMR( Honestly I dont know if they did or did not.) but I dont think that's gonna solve the issue you run into when Theres low player populations.
So back to the topic. No, I don't think the problem with Positional was related to auto fill. If anything the entire system looked to me like riots attempt to fix the frustration people had with getting auto filled.
Far as enjoying the game, that's about knowing yourself and what you want. So personally I have a lot of faith in my ability to climb to high gold and low plat as long as I stick to mains and grind games away. I dont always enjoy this so what I do is usually play off roles or try new strategy's during preseason and spend most the year doing that until I decide its time to grind away to fix my MMR. Given that you need to pay constant attention to your condition when your grinding... its honestly a chore at times.
So that's how I enjoy league, Try new stuff in Preseason then spend as much of the year as you want playing to win with picks and strategy's you like, honestly this is entirely fine. You wont hurt teammates badly compaired to just swaping to a compleatly new role or champion because Placement games and K factor being high is gonna give you big window to bleed away MMR into lower tiers if your not able to preform off roles and champions as well as your polished mains. If you really want to bleed away mmr during a season you can que with friends/players as far below your division as you can. The MM range this makes is insane for most folks and will create a lot of garbage matches... many of which will not favor your team especialy if your not doing your best role and champs. Its.... Kinda soft inting but if your honestly playing to win and so is your duo its not the worst thing and ya lower the negative impact to only 30% of the matches players. I duo with friends who really want to play ranked because I think the times they have to deal with higher MMR players that outclass them tends to be a valuable lesson and again I have faith I can fix my MMR with effort.
With I messed around more in preseason thou, I did not do that this year and I regret it a bit. I grinded like 80 ish games of bard in Preseason to hit Plat to prove a point to a friend. Currently Grinding again to show that point again and after I hit Plat in solo, well then I will likely spend the majority of the remaining season in flex.
I am the kind of player who really enjoys numbers, math, theory crafting, going off meta. I like winning by doing things on my terms. I frequently link folks on Boards to this article about player "psychographic profiles" in MTG.
I think "Jhonnys/Jennys" are the smallest portion of the lol playerbase but that might be my bias speaking. Plenty of Timmys with their LCS BIG PLAYS spamming champions like
. And Heeeeellllaaa Spikes trying to copy and paste what ever looks strong.
Well that's just some of my views and philosophy. Hope it was a semi helpful or entertaining read for you.