Seems you're paying attention to it, but not coherently understanding it.
Sickle Cell anemia and Muscular dystrophy are both monogenic diseases. Treating a polygenic disease is a lot harder, even with current technologies as its more likely to create off-side edits which occur quite frequently.. potentially creating worse issues than the initial disease.
There's a glass ceiling to the technology, for various reasons. The editing techniques are much better than they use to be, but they're still far from high quality enough to be able to treat polygenic disorders. On top of that, we still don't understand how certain genes interact with each other and all their purposes. Until the technology evolves and we have a full understanding of genetic crosstalk there won't be much advances in the field.
Most researchers aren't excited for treating people with diseases via crispr, they're interested in using crispr-a and crispr-i to modulate genetic expression to understand how genes work and interact with each eachother. Research is still juvenile in that respect.