Microsoft not to blame for once
The fault lies squarely with the export restrictions that the US government placed in the 1990s which prohibited browsers being shipped to places like South Korea with strong encryption. Where encryption was required then plugins were the only way and Active X, for better or worse, was better integrated than most.
Yes, the export restrictions were lifted a few years ago but, as we all know, it takes a concerted effort to overcome the inertia of replacing existing systems. Often laws, accompanied by generous subsidies, are the only way to initiate change.