Never worked in the industry (and don't have a desire - though one time I did), but I'd have to say that's spot on. You can have all the fancy shader tech and other 3d gismo engine whatever at hand, but without the story/plot and creative content, anything you made using it wouldn't amount to much.
...and that content is very difficult to make! Even a simple 2D game can have a load of content and design behind it that can't be easily replicated for a new title by a single person. Though this kinda argues against why more companies don't release their engines and tech as open source - especially once the tech has "aged out" (fortunately, a few companies have - like Id Software, among a couple others).
Even with these releases, though, you don't see a slew of others coming out with games and such based on the code.