Just skimming through the article you posted, it says trials with a similar treatment resulted in one patient dying from a massive immune response and two other got cancer. Sounds like it relies on a virus to deliver the DNA, but I didn't read too carefully, so maybe CRISPR will turn out to have fewer side effects or a greater success rate. I'm pretty sure one of the up-sides to CRISPR is compared to other gene-editing techniques it's relatively cheap, which is always a plus.
The NIH study uses a modified HIV to introduce the complete gene for the defective protein.
https://www.nhlbi.nih.gov/news/2019/sickle-cell-patients-rec...
This study uses CRISPR/Cas9 to increase expression of a gene that the patients already have.