I know, I know, its probably largely because I'm right under the fattest part of the MMR average curve, so the quality of players im matched with can be highly volatile, I get that this is the reason for it, but good lord it feels like shit.
I am pretty vocal about not letting people use provably wrong excuses for MM, but your entirely correct about individual match quality issues generated with the curve location.
Despite telling people over and over how Forced and rigged MM is a BS theory. There are legitimate things that will be frustrating as all hell. Being near the center of the curves rough. You have the misplaced players sinking, You have misplaced players climbing. Center sees the most chaos and its also the highest population of players by definition and design.
I am always down for QOL, MM on Riots end can see improvements. Some of that's community related, setting the right expectations. Blending new accounts into the curve is necessary, Does not take the sting out of the match. Even if Riot published what protections are in place or how many games K variable needs before it slows down, it is reactive after the fact MMR algorithm that protects some ones rating. The game that went to shit is going to still be awful. Couple weeks back I demoted 3 divisions due to low quality games caused by player behavior, I blame the players for that.
As long as there is enough population in the que, You can have MM look to match K variables/# of games. Putting weight on say building teams where there is as many players with a "veterans" badge. Trying to keep people from being placed RNG into back to back high uncertainty games.
I don't know what riot does, I do know I have not seen any comments in their publications that their MM puts weight on experience/uncertainty. Its part of why I will tell folks I think their system has to much weight on quick games. Open to being wrong, this is my opinion and thus helps folks understand my Bias.
But forced promos are silly. There's no need to make them any harder, hell most players seem to do that for themselves by freaking out and "trying harder" to win during promos. I don't get that, how you played consistently prior is literally how you got into a promo series to start with. Freaking out and changing your playstyle or losing you head with teammates is shooting yourself in the foot. Now I said you, to its a hypothetical person not intended to represent YOU specifically. Its observable in games, folks who scream IM IN PROMOS DONT FK UP IDIOTS. Rage in all chat, Or say "in promos" Then play balls to the wall aggressive trying to snowball hard carry and feed their asses off doing it.
Personally, I don't give a shit about promos, that's my mentality. https://imgur.com/a/489AYlE That's the result. From G4 to P4. I failed 1 set and lost all of 3 games inside of a promo. I used to care a lot in earlier years, Till I learned more about how and why an accounts MMR > Rank. To show some players how little promotional series mattered I took extra time and effort to build a super large Gap of MMR and rank on My support alt.
https://na.op.gg/summoner/userName=NotNotkaiguy In doing so, I completely skipped every promo from B1 to S1. The only set I played was the G4 promos and I did that only because my MMR was to low and it was very time consuming to dodge lobbies to fail series over and over and my net MMR income was not dramatic enough. As some one who claims to be High Gold to Low Plat there is nothing to shocking in the results. Pretty much as expected, on my main and on my alt.
Smurfs do damage the game, partly because to get lower on the ladder requires losses. Dodge and remake don't remove MMR. It needs to be legit losses. So... they aim to force losses. To keep a smurf in lower MMR, you have to balance wins/losses. So they Stomp and Throw games. That's a negative for quality. They don't however keep people down single handedly.
Hypothetically,
If Riot Did want to make some devious "prove it" Promo system. As I think the priority is faster que time so rather then sit and look and hope you have the random resources in the que to artificially add difficulty, There is a really simple way to do so with out looking to force teams, and with out relying RNG human behavior. All they have to do is change your MMR value to represent the Mean value for the Rank-Division MMR range if your MMR is lower then the range your aiming to promote into, that only impacts accounts who are established with low K variables as the MMR to rank gap doesn't get as dramatic.
That impacts all accounts, it does not require proactive searching, it does not impact que creation times, and it screws folks trying to abuse Duo or lowered MMR to creep into a higher Rank, and all ya need is the ability to function into that range for it to not be a negative impact. Given match averages, I don't think Riot does this. Just that there's a pretty easy and logical way to make it "gatekeeper" with out having to try and control results.
Feel free to hit me up if ya want a hand. No one really seems willing to listen so just gonna try to walk my talk more.