SDS, some of the issues are real, and some are political, and they go WAY back.
UTD was started by Andrew Georgitsis and Jeff Seckendorff. I don't know Jeff's history, really, but I know a fair bit of Andrew's. He was training director for GUE for a period of time, and was the designer of the Fundamentals class. He had a falling out with the organization in about 2005 or 6, and left; he had a virtual dive shop in Monterey called 5thD-X for a time, but that eventually fizzled, and he started UTD. His core ideals are similar to GUE's: Standardized equipment and procedures, standard gases, and high standards for training and performance. But unlike GUE, Andrew tried to incorporate sidemount and CCR into a single model that would permit mixed team diving in a seamless fashion. This is one of the areas where there is a lot of controversy and negativity. Neither the core DIR folks nor the CCR folks liked the UTD CCR setup; neither the core DIR folks nor the dedicated sidemount people like the manifolded sidemount arrangement (and for good reason, in my opinion).
So you start with the fact that about 90% of the diving world that is even aware of what the DIR approach is, doesn't like it, and you add that two-thirds of the DIR world don't like some of what AG and Jeff are doing, and you end up backed into a corner where you aren't very popular.
Two of the best instructors in Seattle are UTD instructors. I took my Tech class from Brian Wiederspan and respect him and Jeanna enormously. I dive 25/25, because I think it's a gas that makes sense for the dives I do, even though it isn't a GUE standard gas. So you can see that I am not a UTD-hater, because I have taken their classes (I've got a card from AG). But I think there are things that are worth criticizing.