There is no part of the non-expert interface that suggests this should.

If we say we support SPARQL, however, we should support as much of it as
possible. Correct me if I'm wrong, but filters and operators are part of the
core spec, no?

I'm downgrading this to 'feature', however, because it's more a "this is a
feature we say we support but don't" instead of "this is something that should
work but doesn't".