That's still best achieved with SBMM (just a less strict version). With random matchmaking, you are only equally likely to see better/worse players if you are in the 50th percentile.

Also, each player is independently selected (when random). This means there will probably be a mix of high skilled and noob players in every game. You would not see a team of mostly noobs or mostly pros. For a player in the 50th percentile, with a team of 6, the chance of being better than every player on the other team team is only 1.5%. For the 25th percentile, it is 0.02%. So a very significant number of players would (almost) never experience an "insane spee on noobs". However, the chance of having at least one player in the 75th percentile on the opposing team is 82%. So they would frequently encounter situations in which they feel hopelessly outmatched.

The only way to solve this is to use matchmaking that attempts to take skill into account.