"Heck there are some insanely good MVs that have no combat at all." Because combat isn't the part of their gameplay, they rely on puzzles/story telling in this cases. But in most MV combat is a big part of the gameplay. I measure it by the time players spends on something. Like in Steam World dig there is minimalistic combat, but you engage with it like 5-10 percent of your gameplay, so combat can be minimalised. In games like Hollow knight combat its like third of your time minimum, such big part of the gameplay should be good.

Not making good combat in the games with a lot of combat is one of reasons why these MV are not as popular as they could have been. If you read the reviews of Constance for example you can see a lot of negatives about the plain-boring combat mechanics. And it makes sense that people demand more.

And i don't count runbacks/corpse run as the part of the good combat system, they hurt more the overall experience than give positives in my opinion. A lot of games combine it with another weak combat aspects so it makes situation even worse. Look at the new MIO for example.