I used to do research on HCV. HCV was curable for at least 10 years prior to Sovaldi, the issue was that the Ribavarin and peg-interferon treatment typically took 48 weeks, had a cure rate around 50% at best if you had the right HCV genotype, and had many adverse effects. The epidemic is currently being driven (at least in western countries) by active drug users, treating them with that regime was simply not possible.

Contrast that with 8 weeks or less of 1 pill per day (and possibly less), with no side effects, pangenotypic and >95% efficacy for all (including cirrhotic individuals, HIV co-infected, etc)