I was still speaking historically, so I meant before easy checks like your ID were in place. Its definitely harder to do that, nowadays. But of course they can go after you for it, that’s my point. You’ve agreed to a contract by the act of signing anything. If I forge a name of a nonexistent person, they can still go after me as if I’d signed it normally, because the act of signing at all is what binds me, not what I actually sign. I held the pen, I agreed to the contract. It would be ridiculous to escape legal consequences by doing things like signing differently, and in this area of law, at least in the US, common sense prevailed and I’ll be liable for whatever I willingly signed, whether that’s my name, an X, a fingerprint, a fake name, or anything else.