It wasn't stupid of you, not your fault LinkedIn literally impersonated you. The mail it sent out all those years ago was written in your name and as though you had actively crafted and sent it. Anyone who knows your name could have impersonated you. Don't worry about doing something wrong.
A quick google suggests linkedin was sued and reached a class action settlement in exchange for the practice.
A quick google suggests linkedin was sued and reached a class action settlement in exchange for the practice.