Perhaps Yes Scotland failed where the Brexiteers and Trump succeeded because the SNP and their allies offered a plan whereas the others offered something based on emotion. Your opposition can pick holes in a plan, even a 600 page one, and doing so makes them look mature and considered. They can’t pick holes in an emotional connection, especially not one based voters’ hunger for better lives for their communities. If they do, they look uncaring. The Brexiteers and Trump tapped into people’s hopes and fears not only for themselves but for ‘folk round here’, which, in each case, was extended to mean the whole nation, as least as far as their supporters saw it. When the SNP appeal to emotion, they do well. 2007's ‘It’s Time’ connected with people in a way not unlike ‘Make American Great Again’. Each lit a fire in the bellies of voters who wanted to throw out the establishment. Look at who lost in 2016. In the Brexit referendum, it was the side with the deal it had negotiated with Brussels. In the USA, it was the candidate with more policy expertise but less ability to connect with people. In the pursuit of power, passion beats reason.