The large-scale structure of our Universe is well described by a model in which matter is predominantly Cold Dark Matter (CDM). While CDM was initially thought to have trouble reproducing the small scales of our Universe (dwarf galaxies and the central regions of galaxies like the Milky Way), it has generally become accepted in the last decade that a proper treatment of the gas and stars (baryonic matter) can alleviate those tensions.  However, the models of energetic "feedback" from stars that have solved some of the tensions in CDM are now running into trouble solving new problems, specifically the "diversity of rotation curves" problem. In this talk, I will highlight the successes and troubles of current baryonic models, and discuss whether self-interacting dark matter (SIDM) might be a better model to explain observations.