I’ve posted previously (Theme Standardization Through “Feature” Support) about the possibility that Hugo could create space/scaffolding for community-contributed theme tests (and probably the first few examples), which users can use to evaluate their site, developers can use to evaluate their themes, and the theme site could use to communicate (and cross-link) themes that pass the same feature test.
It’d be more chaotic than an One Interface to Rule Them All, but it’d let us haggle towards a standard definition of a given feature (even those of us not directly developing themes, since we can still contribute and advocate for improvements to a feature test that will nudge the ecosystem in the right direction.