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I didn't say they were non-existant, they were not popular.
Again, history says otherwise. Arianism only appeared with Arius. Prior to that it was the teaching of the Trinity that was within the core of orthoxy - by your definition - it was popular. Prior to Arius were the various gnostic sects that attempted to appropriate Christianity as its own with their aberant teaching on God. Gnosticism never gained traction within orthodox Christian teachings - never 'popular' by your definition.
So if Trinitarism was not 'popular' cite sources for what WAS more popular then.