I think they fear DE a little too much, unfortunately. Too many universities have a strong incentive to limit DE credit received same as they have a strong incentive to limit AP credit received. every DE or AP credit is less tuition paid to that university, and that's can be a huge problem for them.
What if institutions' own data shows students who receive AP or related credit do substantially worse in subsequent courses? This isn't always the case, but I have heard of instances where it is true esp. in math and sciences.
I think that incentive is dissipating. Public universities are getting fairly desperate for enrollment and tuition and are realizing they should take in students even if it means they'll pay for a few less courses.