It does not work so well for Combat or even in more general terms Action.But why doesn't that swing the other way? Why is it wonderful and amazing to have a "dense section of rules" for combat, "when we are perfectly fine managing that without it, or with a much smaller set of mechanics"?
Because what this seems to be saying is that combat is somehow radically different from other forms of challenge someone might face, and that's an assertion very much lacking in the proof department. Particularly if we're going to be disparaging one as "dense"--cumbersome, unwieldy, overly-elaborate--while the other is seemingly only positive!
It is simple and easy to role play a character talking their way past some guards. This does not quite work with a character swinging a sword and killing a dragon. The rules ground the game and give it a base line. You want to take an action, you must use this rule.
Combat rules..at there very best...give gamers an illusion of choice. They "think and feel" they can take an action in the game......they can "best the rules" and "win". The dice alone give the feeling of chance. If you have played a couple rpg games you should have seen at least one amazing roll. Once...a small dragon set a trap for some characters...and they fell for it. While stuck in the trap the dragon breathed..............and I rolled a "1", ten times....so for only 10 points of damage. A famous one was the lich battle on the mountian top. Big battle and the PCs nearly loose, all being near death. As the lich telekinickly tosses the paladin off the mountain...he makes one last attack. Throwing his holy dagger at the lich.......and rolls a 20. And does a bare 11 points of damage.....to the lich with 9 hp left.
There are RPGs with simple combat. "ok roll an 11 to kill the dragon".