People always assume this with sites like youtube/facebook/twitter/etc but they forget that the most interesting problems tend to come from the requirements of

People always assume this with sites like youtube/facebook/twitter/etc but they forget that the most interesting problems tend to come from the requirements of scaling. From my experience most people seem to have their wall at which point they can't possibly conceive of a better way to scale X until someone comes along and goes "Try this". My experience also says this level is pretty low for most people.