Yes but it’s precisely this what’s exciting about m+. Chasing the score and the limit. 
I’m curious about this. How so? Are we talking about the first few weeks to farm hero items to get faster progression in mythic raids? Or are we talking about just having 3 more vault options?
WoW has changed the fundamentals of the game so often that this barely counts as an argument tbh.
PvP gear went from not being different to PvE gear to having its own stats to having its own different stats to having no gear at all but templates to having different scaling now.
We have spells have different balancing now in PvP and PvE.
We don’t have attunement quests anymore for dungeons/raids.
We have 4 different raid difficulties now.
We have 3 to 4 different dungeon difficulties now with the last one scaling to infinity.
In vanilla we did dungeons to get pre-bis and then we raided.
Now we do dungeons->hc dungeons->M0->NHC raid->M+/HC raid->M+/Mythic raid. Also put delves somewhere in there as well… and world quests and rep farm.
It’s all over the place anyways.
I hear this a lot and I don’t like the argument at all.
If mythic raids are significantly harder, then I’m supporting this. But just because something is more bothersome to organize, it shouldn’t reward more in a video game.
Now we can argue about mythic raiding being harder than M+, which I can agree on but theoretically speaking, even mythic raids are ultimately designed to be beaten by players while M+ are designed to scale into infinity and therefore can’t be beaten.
Looking at RWF, where the best players beat the raid after 10 days on average while looking at the M+ leaderboards, where new records are still being set at the very end of the season.
Mechanically mythic raids are harder/more complex though, I agree with that.
But having “it’s more of a hassel to get 20 ppl together” shouldn’t be a valid argument in the case of gear progression imo.