James and Orville Wright didn't invent the airplane. Henry Ford didn't invent the automobile. Thomas Edison didn't invent the lightbulb. Ray Croc didn't "invent" McDonald's. James Walton didn't invent EDI or data-driven retailing. etc.
But as an investor, you sure wouldn't go broke investing in them. That's the kind of person you want to set up shop in your town if you care about the economic benefits, not necessarily another PhD developing technology years before its time. ("MIT graduates develop technology. Harvard graduates hire MIT graduates and build businesses." was the old saying.)
I think Boston's non-life-sciences tech scene is doomed for a variety of reasons, but thinking everyone needs to invent one amazing new scientific advance ("idea") to build a world-changing business, vs. lots of correct, incremental decisions along the way ("execution"), is a major reason.