we have proof that it is. the whole debacle with Halo Infinite players. you could easily test it in that game.
I play Fortnite as one of my chill out MP games, and I can basically manipulate the EOMM at this point.
I literally manipulated my way to unlock higher tier versions of the Llama backbling
to unlock the higher versions you need to get a certain amount of kills and placements in the game. the only one I don't have is the final gold one, as that one would take too long to manipulate my way into, and I'm not that good in the game. but I got up to the second to last one (the progress resets each season)
and because I know how to manipulate the EOMM in Fortnite, I can also basically detect it in other games and can tell after a few weeks of playing how strong it is implemented.
in Fortnite you can manipulate it pretty easily while also verifying that it doesn't take your skill level into account, and only tries to manipulate your kill and win rates.
to do that I found a very easy way: Play Ranked...
I am decently ok in Ranked fortnite, my highest rank was Champion rank in Zero Build, which is the second highest you can get.
so here is me playing ranked in Champion rank, against other Champion ranked players, some Elite rank players and some Unreal ranked players mixed in as well. I get 2 or 3 kills, get a top 5 or top 3 placement, enough to rank up in the SECOND HIGHEST RANK in the game.
BUT, getting "only" top 3 or top 5 all the time, and "only" getting like 2 or 3 kills... that's not enough according to the EOMM system Epic Games has implemented here. BUT their system can not manipulate my ranked matches, because those are all matched through rankings not any EOMM shenanigans.
so I am playing and playing, ranked match after ranked match. slowly building up a series of games with no wins, and with "only" 3 kills or so because I am constantly up against the top 3 ranks in the entire game.
GUESS WHAT HAPPENS IF I NOW SWITCH TO NON-RANKED!? after basically blueballing the EOMM system for multiple matches...
you don't have to guess because I will tell you: I will literally get put into a bot match.
and when I say bot match, I am not only talking about low skill players (which often get colloquially called bots) but indeed LITERAL bots, which you can instantly spot as well due to how unnatural they move and react.
so after battling and battling the top rank players, getting good enough results in matches to increase my rank further and slowly inching towards the highest Unreal rank, the moment I play too many of such matches, the EOMM system will say "YOOOO you didn't get a win with 20 kills in a while! HERE YOU GO!"
and of course the opposite will happen if I play too much non-ranked and get too many wins and too many kills per match. what happens then is that I might as well play Champion level ranked matches as the experience will be the same as that or even worse.
this clearly demonstrates that the matchmaking system doesn't take into account my skill level, and only my kill stats and win stats over the last couple of games. a true SKILL BASED system would see me kill high rank players and placing high in high rank matches, and match me with similar players. which doesn't happen, clearly, as literal bot matches are quite the opposite of that. if you don't win such a match that I am talking about here you truly are awful at the game. these are matches with beginners and literal bots that can barely even be classified as opponents... they are shooting range targets
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in Apex Legends I also noticed it, but way less pronounced. and in Call of Duty it's also very obvious. in Halo it prevented some people from finding matches, because the game needs to manipulate not only the enemy team but also YOUR team to make you lose enough to keep you in the "sweetspot" determined by the devs and their EOMM system.
some of the best Halo players tried to queue into games with friends, and as soon as there is 2 of them in a party searching for matches, the matchmaking would go on for literally 40 minutes, because the EOMM system could not find enough SUPER BAD players to manipulate their team, and not enough really good players to manipulate their enemy team. so they were stuck in queue for 40+ minutes. if they lost 2 matches or so it would go back to normal again for a few matches until it would be back to 40min queues