He/she/it is engaging in a strawman by putting that premise up. It's using a strawman to make a blanket generalization, and it's as transparent as a summer day is long.
You cannot "influence" people retroactively before your own birth. The premise is absurd
She didn't say Marx influenced anybody retroactively either. She used the term "Marxist' as it is understood today to describe concepts that leftists attribute to the Founders today. The concepts existed long before Marx wrote them into a political philosophy. But we didn't have a label to put on them until Marx wrote them into a political philosophy. I simply refuse to believe that you are too dense to understand that, so I have to believe by now you are simply too proud to admit that you are wrong.
Are you saying then that there is no difference between "Marxism" and "socialism"?
If so, why did we need the word "Marxism"?
Clearly the term is specific; if you say "Marxist" you're referring to something Karl Marx espoused; if you mean simple 'socialism' --- then you say "socialism". Were there "Keynseian economics" before Keynes was born? Hegelian philosophy before Hegel? Were there "Christians" before Jesus, Islam before Mohammed, Buddhism before Buddha? Did Plato pusilaminously plagiarize the past platonic?
I've never heard leftists, or anyone else, propose that the Founders were that prescient; Kaz's insertion of that canard as if it's a fait accompli comprises a strawman. But I've since read the poster has left town and may not be reading all this, so it would be unfair to pile on this point before his/her/its return.