Why people still insist on using ZSNES? It was never that accurate to begin with (on the contrary, many emulation errors and freezes every other emulator already fixed long ago).
The same reason people still do anything that's technically bad: they form habits, create a comfort zone, and don't want to leave it. Are there are better options than ZSNES? Sure! Even SNES9X is better than ZSNES, and really people should be using bsnes or Higan.
But if it works for them, and they're comfortable using it, it's not the end of the world. To some people, emulators are scary, complex things that require a lot of setup to use enjoyably.
That's the one reason I don't like talking about emulators in my "Definitive Way" videos, because I'd want to do more than just gloss over what all the settings do. Depending on the emulator, just setting up the controller configuration would take multiple minutes.
Even if most SNES emulators are relatively simple to set up, there's still a stigma that emulation in general is hard to deal with.