You are missing couple of points : awareness of such tool, downloading of huge archives, and strong collection interest in people. I know people who.str happy to play Mario look-alike.js game instead of figuring out retroarch.
Last point : flash games peaked when rest of the world didn't have very fast interest. Only 0.1% had it or interested in it
Last point : flash games peaked when rest of the world didn't have very fast interest. Only 0.1% had it or interested in it