Why don't they sue PC manufacturers for producing the hardware that led to the emulator?
This one is perfectly analogous to the Nintendo tomfoolery, though.
Not really. PCs aren't purpose build to run emulators, these emulators just happen to also work on them.
Emulators on the other hand are purpose build to circumvent anti piracy measures (which is illegal even for your own use), even if piracy may not be their primary intention.