Because there is not a scintilla of evidence for this creator, just specious arguments that are shouted ceaslessly by believers until the only ones they convince are themselves.
The definition of Creator means "coming from something or someone," however I think the association of creator with a god or gods is why unbelievers steer clear of the word.
In late middle english create means "to form out of nothing, usually in relation to a divine presence or supernatural being," from Latin creare.