The two part pour was because stout used to be served gravity fed from a ' low cask ' near flat and a 'high cask ' with a lot of foam in it for a bit of head. When they switched to keg they kept the 2 stage pour because twas what they were used to.
I've seen this gimmick of the skim a good while back in Holland. I think it was a fill it to the top kind of thing. The dutch are, eh, frugal.