PrunellaUK
Tea-stained crumpet-ridden idiot
I find this is not true for a variety of reasons.
Rules light and rules heavy are not synonyms for rules complete. A rules light game can be more rules complete than a rules heavy game in that for example it maps all player propositions to some small set of defined moves that they can perform. Players can be as creative as they like in describing and narrating their moves, but at the end of the day they are all just moves and mechanically all that narration has little or no meaning at all. This means that all but the most expressive narration driven groups will in the long run default to just stating the move that they intend because what they state doesn't matter anyway. Combat almost always devolves down to stating a series of moves and performing the mechanic, and this is true even of rules light systems that aren't rules complete (like BECMI).
Rules light systems give GMs very few levers to pull to adjudicate a player proposition. The more rules I have and the more things that the rules account for and can interact with, the more I can translate creative propositions into mechanically distinct and meaningful acts with real outcomes rather than just the color of outcomes.
One thing that might be the case is that in a rules light game the limits of your character as a playing piece are often much less coherently defined. In a rules light game, because literally everything is on fiat, it's easier to be generous with character propositions into areas that the rules are silent on because the rules don't say the character sucks at whatever they are trying to do.
This does not compute for me. Outcomes for a light system aren't any less real than outcomes for a crunchy system. This appears to be an assertion that more detail and process is somehow more concrete than less. It's assigning a qualitative value to crunch. Or, to inject the title of a VERY old British sitcom: "Never mind the quality, feel the width."