I have been mulling on this as a result of these threads and a
Matt Colville video. I am thinking that it is not really about combat but combat is the bifurcation point. One play style "Combat as War" is really about Operational Resource Management. By that I mean the use of diegetic resources (Inventory, environment, allies, intelligence (as in information about the enemy) to leverage an advantage in combat.
This supports a number of playstyles but the emphasis is on gritty. Combat is dangerous, the environment is dangerous and poor planning will kill you.
It is also about using resources not native to the character to prevail.
The other playstyle is what I call Protagonist style. This is the character is a hero, has a certain amount of plot protection and has the internal resources to prevail.
This supports any kind of narrative or story focused play (even if that story is an emergent story from some kind of sandbox) it is not easy for the DM to accidentally kill the PCs but still possible to set up challenging encounters and that 5e strongly supports this style. Particularly since I think this style strongly supports casual play.
I also believe that as long as D&D is designed with public playtesting it will favour this type of game.
I think to shift the game toward Operational Play, a number of steps would have to be taken. Separating hit point recovery from power recovery and rule options for both.
More detail on the math of the game, what is the expected damage output of a party per level and that of a CR x encounter and how to take into account action stealing effects to allow DMs to more finely tune encounters and to tell if their party is punching over its weight and by how much.