I meant as far as randos doing it, not companies wanting to make more money off their own IP.
Well, same as anything else related to hobbies. ZSNES and Snes9X both could play every SNES game. But byuu wanted a cycle accurate emulator. bsnes caused both ZSNES and Snes9X to come back from the dead, if briefly, to patch out bugs and rewrite bad code hacks.
As an aside, byuu couldn't rely on ROMs (many of which have been dumped multiple times, the various "packs" have reasons behind their redumps, etc. Same with how they're re-ripping all the Dreamcast games again) he had to use actual hardware to check against. One reason for years he never would refer to it as 100% accurate is because it's almost impossible to recreate the effects of the sound chip without using the actual chip. The Genesis emulators all have this problem too, including the one Sega purchased from "a rando" to use as their emulator.
