The thing is at 2/5th of people getting loot each mythic+ takes 30 min. If you do 4 heroic bosses in a pug that will take you an hour or a little more you might get 1 piece of loot on average. If you do 3 mythic+ you have around the same chance at getting 1 piece of loot on average. Personal loot is about 25% chance per in raids these days. So mythic+ is equal to personal loot so for anyone not doing organized raiding Mythic+ is equal or better than raids still.
And with mythic+ you dont have to grind anything outside the first week. Once your keystone is 10 it only resets -2 levels a week. So week 1 you may have to do 7-8 dungeons to get your +10 for your 880 ilvl cache at end of week but week 2-3 you will only have to do 1-2 dungeons to get it.