Players vs. Rules

One sentiment I've encountered in regards to tabletop RPGs quite a few times is a variant of the belief that system doesn't really matter: an RPG "can't be all players/can't be all rules".

I'm not exactly sure how to unpack this statement.  On the surface, it sort of seems absurd.  After all, games are exactly sets of rules.  So saying it's not "all rules" doesn't make sense.  After all, if you take away the rules, what are you left with?

I think the intent behind this idea is that so-called mechanical solutions aren't appropriate for many instances of play.  But I think this is a misunderstanding of what mechanics are.  I think, what this really is, is a stance against rules-heavy simulationist style play.

But that's not "rules vs. player", it's players applying a certain set of rules.  I don't think the "system" in "system matters" just boils down to dice mechanics.  "Describe what your character does, GM decides results" is a universal role-playing system that promotes a certain style of play.