If you have access to the iTunes account you can do a physical backup with iTunes and then erase and restore that backup. It won't be pin protected.

How would one connect the phone to iTunes to do this? You must enter the PIN on the phone to connect to iTunes iirc.

Not to do a backup and restore.

Not even sure what you mean by "iTunes account"?

Errr, sorry I think it's called iCloud now :P

Apple ID

Not that I know of. Like others have said you can pull a backup (but the machine backing up had to have been trusted prior or you're SOL) and then restore the phone.

Nothing's bulletproof but the iPhone is the most trustworthy IMHO.

I believe this is to deter theft.

I've locked out my galaxy s6 using the wrong password and it just wiped and reinstalled by itself. Then allowed me to restored everything that was on cloud backup.