I think people have very little concept of how much 2TB is or how fast 2.4Ghz is. One fusion-io card can cope with a phenomenal amount of io.

They've bought the story that RDBMS don't perform at web scale without considering if their systems are now or ever will be performing at this remarkably unquantified level.

I get the developer's need for a flexible data model in a fast evolving system and that is fine for an extremely simplistic business model. The instant you want to make broader use of your data convenience at the front end translates to short term gain for long term pain