Rings is technically a filter (yes, a physically-modelled resonator...but that's a very fancy DSP-ish filter, ultimately) and even if doing self-resonating things, you'll get a limited palette of Rings-generated sounds. I think you're thinking more of the Mutable Elements here...which is the Rings plus a modelled vibration source. Even so, without VCAs, modulation sources, etc, the results would be sort of meh. With the ES modules, you can have Silent Way generate modulation, which helps...but without similar audio signal control, you lose a lot.