ΛCDM simulations with cold, collisionless dark matter generically predict that galaxies of similar halo mass should have broadly similar inner rotation curves, reflecting a near-universal NFW-like density profile with modest scatter (Navarro et al. 1997; Oman et al. 2015). Observations instead reveal a wide diversity of rotation curve shapes at fixed mass—from slowly rising, core-like profiles to steeply rising, cusp-like ones—along with tight empirical relations between baryonic distributions and rotation speeds, which are difficult to reconcile with a simple, universal dark matter profile and require finely tuned baryonic feedback or alternative gravity/dark sector models (McGaugh et al. 2016; Oman et al. 2015).