While some people argue still against the first key squish, there were a lot more levels nobody did and we can see now that there still are a lot of pointless levels in the 2-10 range. Even listing a key with both a tank and healer on a non-threshold key in the 2-10 range can take 5 minutes before you even see a single DPS apply, which isn’t a lot of time, but compared to useful key levels that instantly get 10+ applicants it’s a significant difference.
I don’t think M+ needs more than 4 difficulties in the gearing range that’s currently 9. Raids only have 4 difficulties as well. Ladder pushing can then start on 6 with 5 being equivalent to the current 10 with mythic vault, 4 starting to drop gilded crests. Hero drops can start on 4 as well if 4 is basically a 7 though you could also make 3 close to a 6 and start hero drops there. 6 and 7 are both currently popular and 3, 4, 5 8 and 9 are just an annoyance when trying to get a key you actually want to use.
Anyway, something to note is people only see your M+ rating and dungeon completed when their key is listed in the M+ section. Sometimes the person with the key doesn’t want to lead (like any of my friends that always make me invite for their keys) so you have to list their key under the mythic dungeon section instead. If you’re trying to find a less picky group those groups can only see your class/spec/ilvl.
Using the premade groups filter addon also makes it easier to find groups under a variety of conditions that may make it easier to get into groups faster.