On my machine, the initial state isn't simulated. It only begins simulation when I touch it. At which point, the weight causes the bottom blocks to intersect each other significantly.
If I open it, click on the background to activate the physics and just keep the tab open, pretty much all of the blocks that can collapse do eventually collapse.
One more pedantic nitpick: when a block gets wedged between two blocks at an angle, it gets slowly pushed out, although there is a lot of weight resting on the top block. That would be realistic only (maybe) if the blocks were made of ice, but not for other materials...