[jezzamon]

Depends what you're trying to do, but some glitches used in speed runs literally depend on the exact values of pixels on the screen

https://youtu.be/0B095eHBrCg?t=24m40s

Not saying that supporting glitches like that is a hard requirement for these ports though

[jamesgeck0]

Inaccurate emulation can also result in stuff like altered physics, invisible objects, stuttering animations, etc. resulting in a different experience from the original.