Veloswap is tomorrow. I'll be there, FWIW.
The reason 29" bikes are better is mostly momentum and rolling inertia. You remember physics, right? The mass is farther away from the axle, so they tend to carry more energy than a 26" wheel. Harder to accelerate, too. Also the larger diameter means more contact patch, so that factors in. I don't personally think it's got to do with obstacles being spaced or sized on 26" wheels, but I dunno. There's so many different variables with bikes, less spinning on obstacles than trucks, so stuff isn't dug out on the climbs as much as washed out from erosion. I do think hardtail vs. suspension and wheelbase of the bike and where my fat butt is positioned relative to the front/rear makes a significant difference in how a bike handles. A 10mm longer stem or bumping the saddle back 10mm changes the handling quite a bit.
"Why does the U.S. care which flag will be hoisted on a small piece of land thousands of miles away?" -- Ron Paul