As usual capitalism encourages ppl to look at individual rather than system. Almost everything we associate w/ the term "blockbuster" from the summer, to marketing, to what the movies look/feel like is a result not of frequent inspiration, but a near mandate as a response to the success of Spielberg's film by the industry.
Saying Spielberg is the sole reason Hollywood is the way it is today lets many producers and executives (who are still working) off the hook.