Why aren't the leaderboard unfiltered by default, but instead hide the emulator runs?

To clearly indicate emulator runs are not fairly comparable to runs on real consoles. Emulators usually have a lot less lag than the N64 Console for real time speedruns and so are hidden by default. It's an advantage over players recording gameplay from a N64.

To build on what Ghillie said, several other games hide emulator runs by default for the exact reasons he said. It's just to be fair to console runners.