man of straw (or straw man)
1 a person compared to an effigy stuffed with straw; a sham.
2 a sham argument set up to be defeated, usually as a means of avoiding having to tackle an opponent's real arguments.
❷ 2013 Bryan Caplan, Arnold Kling & David HendersonLibrary of Economics & Liberty It sets up as a straw man a perfect, frictionless market and then concludes that because in reality there are no such things, the case for free markets is thereby undermined.