‘-ism’ is an appropriate english suffix for someone holding tightly to or advocating for believe or system. Seems less cumbersome to use than than to use ‘proponents of Evolutionary theory’.
That's true, but the folks who use the term "Darwinist" (99.9% of the time) are creationists who are intent on denigrating the sciences in general and the evolutionary sciences in particular.
When I see that term I don't have to search too deeply to see where the article is coming from. And I have never found a scientific article in a peer-reviewed scientific journal that was littered top to bottom with "Darwinist" this and "Darwinist" that.
Nor have I ever heard scientists or students in the broad fields that make up the study of evolution use that term to refer to each other--and I spent six years studying in those fields in grad school.
No, "Darwinist" is the creationists' new "D" word, used with about as much reason and logic as the earlier "N" word.