It’s true that one reason some systems are light is that they don’t
have enough of a gloracle, i.e. the light systems passes the buck to
the GM’s whim instead. I’m not into that.
But there are three other, better reasons why a particular system is
be lighter.
They can have coarser granularity. C.f. Three Sixteen that just has
a single “Fighting Ability” stat, vs systems where defense and
offense are separated, vs something like Mythras where every body
part has its own stats.
They can have made better design decisions on a different “layer”
of the system. C.f. how Fate tabulates point value of disadvantages
during play instead of how GURPS tries to estimate & charge their
costs pre-hoc. That means GURPS both needs to have a pre-written
list of disads, and point values for those lists tabulated. While
Fate can make disads a lot more open ended and people can write
whatever they want.
They can use more general mechanical solutions and repurpose them
for different roles rather than having mechanically different
subsystems. In some OSR games you save by rolling high but you do
ability checks by rolling low is an example of that kind of
complexity that could instead’ve been easily elidable. (With
hindsight.)
