Why is this so hard to get? The wallpaper is just a proxy for what he's talking about. You can't lay out a bunch of apps spanning his 6-monitor setup in one space, then a completely different set of apps spanning the array on another space, and then switch between those two spaces. That context is lost entirely with this arrangement.
Then why didn't he do that? It would have been easy to do. Why would he purposefully abstract his problem?
And seriously, everyone bitched and moaned about all spaces switching together. They all wanted to do it on an individual screen basis. Now they're apparently getting that and it's wrong all of a sudden? Wow.