Piracy isn’t about preservation. Piracy doesn’t create the roms. It’s the dudes with rom dump devices who do that. And making archival copies isn’t necessarily piracy.
But yes, piracy is the only practical way for new customers to access older content that is no longer sold.
Gecko? Do you mean Blink?
Gecko is the name of Firefox’s renderer. Blink is the name of chrome’s. WebKit is the name of Safari’s.
It would not be correct to say that Safari uses Chrome’s renderer, but since Chrome started as a fork of WebKit, they should have some similarities.
But there is no genetic relationship whatsoever between Gecko and Safari.