Will your preferred code editor warn the original author that you just cut an pasted some copyrighted code into it? How would it even know?

It allows inserting more than one line because it is dumb and can not know if the piece of code it referenced is copyrighted or not and who wrote it. It just looks at the immediate context of the place of your cursor, then looks at its database where it says “usually these three words are followed by these other three words or letters” and then suggests that (very simplified speaking).

And no it is not anywhere close to the Piratebay ;)