I specifically ignored Challenge Modes because you are against any sorta “go go go” mentality, and those live on in CMs faaar more than any m+.
And that is correct. M+s do not scale to your ilvl. They scale to your skill level. If you are good enough, you get a better one. No “go go go” mentality is required.
I rush around in leveling dungeons far more than most m+ I do, while still regularly doing keys 10 and higher.