exactly as you say, an argument for UBI doesn't necessarily need to mean retreading the whole history of UBI designs and legislatures, it just means someone would like to UBI exist without necessarily having to be an expert on how to implement it. I wanted to eat some sushi today and I didn't start questioning myself "well how would you evolve sushi rice starting with a wild rice cultivar", i just went to the store and bought it and now i'm fine. there are experts for that sort of thing and I leave it up to them. I guess if someone doesn't realize there are experts for topics then that betrays they think they are an expert with everything.