The pushback is that nobody actually KNOWS if it is a miracle drug or making a difference because all of the evidence right now is strictly annectdotal, so people are pumping the brakes regarding the PR around it because it could potentially be DANGEROUS, and it also may provide false hope.  

Reading an article about a famous law blogger who had to be hospitalized and things were seemingly tenuous at best for a time before he recovered.  He mentioned that among multiple different treatments he received was hydroxychloroquine and z-packs as the doctors were trying anything to save his life.  Because of that they don't know if it was THAT or one of the other treatments, or if his body simply stepped up and finally fought it off.  

They did take vials and vials of his blood to test, but it will be hard to be conclusive for him in particular on what actually helped him defeat the disease.  

In this information age we expect things to happen fast, and we think there is evidence there when it isn't really true.  A hero of hydroxychloroquine, Zev Zelenko, is now being discredited somewhat by his colleagues and those other doctors who have treated his patients.  As I've posted here, his numbers were suspect from the get-go, and his 100% cure rate also appears to not be true.  Right now less than ten of his patients are hospitalized with at least two on ventilators.  With those numbers and his claim of treating over 600 patients with COVID-19, it would appear that his success rate is no better than a placebo (if 95% of those who get it have mild cases).

So... with some additonal light on Dr Zelenko's findings, it may not be so great.  Once again, I really really hope it is the cure and we can all get back to our lives.  But color me very skeptical.