The dictionaries are a bit vague about what an aphorist is. They say a poet writes poems and a novelist writes novels but an aphorist either "writes" or "utters" or "formulates" or "repeats" or "collects" aphorisms.
A few historical and modern figures are sometimes referred to as aphorists but I doubt that they would have accepted that as their principal identity. They were "philosophers", "statesmen", "prophets", "thinkers" or "holy men".
My definition of aphorist is "a lifetime writer of uncategorized aphorisms". There has never been such an aphorist. The temptation to become an essayist was too great.