ngrams viewer: complexifier,complicator. Looking at ngrams, it seems complexifier arose in the 1960’s and overtopped complicator in usage in the early 2000’s.
Word comes up because of a Jeff Bezos Medium post to the National Enquirer about a year ago (“No Thankyou, Mr. Pecker“, 2/7/19), in which he says that ownership of the Washington Post was a “complexifier” for him. I didn’t like the newfangled sound of complexifier, yet had to admit the more established complicator sounded outmoded or, for other reasons, not quite right. Would myself probably have said that owning the Post “made things complicated for me.”
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