This "classic tale" you mention has basically only happened once or twice, as long as I'm understanding you.
If you mean "often times scenimatic cgi trailers look nothing like the game" then yeah that's fair.
If you mean "this in engine trailer looks way better than the game that launched as far as fidelity is concerned" then there are no legitimate examples I've seen besides Watch Dogs 1. The spiderman puddle was a complete hallucination, as was every other example I've seen.