Tangentialist

Someone who agrees to do something specific but becomes distracted and goes off in all directions, like Captain Wrongway Peachfuzz

He agreed to take out the trash but then he, being a tangentialist, went through the trash instead, focusing intently on each item, having decided that YOU don't know what constitutes trash, and that he needs to decide.

He micromanages by being a tangentialist, spiraling Brainiac style into the project - trouble is, he misses the target. By a country mile.

tangentialist

(n) person; someone who engages in tangental speech, a communication disorder in which the train of thought of the speaker wanders and shows a lack of focus, never returning to the initial topic of the conversation. Symptoms include unnecessary detail and storytelling that only slightly relates to the original topic or never reaches a conclusion.

The tangentialist Playful_Barber_8131 heard the word "peanut" in conversation, then proceeded to describe how the word origin is derived from the fact that peanuts are legumes and thus related to peas, hence "pea" + "nut" to get the word "peanut," and then went on to describe another fun fact about how American cheese doesn't have enough cheese in it to qualify as real cheese, so it's actually called a "processed cheese food," and that even though they like American cheese they like cheddar cheese a lot more, especially sharp English cheddar, as Cheddar is the epynmous place after which the cheese is named, and it's so interesting how a lot of foods are named after places and the food becomes more famous than the place, like champagne, and so on and so forth, never again returning to the original topic of conversation, which was "do you have any allergies?"