I am confused here. In the post#28 of the thread below, I have been told that "English speaker" is a noun+noun combination.
Here you're saying that "hard worker" is adjective+noun combination.
You are comparing apples and oranges. The examples have nothing in common, so cannot lead to confusion.
In particular, there is no "very" in the "English speaker" example.
"hard" is an adjective. "worker" is a noun. What is "hard worker" in terms of grammar?
A noun phrase which, as Myridon observes, is incomplete.
"A hard worker" and "a very hard worker" are also noun phrases.