It's true that nothing really stops you from just doing it, but in my opinion without anyone there to anticipate your accomplishment it's hard to motivate your self. Sure if you have natural talent, meaning you can naturally generate motivation without anyone's positive feedback. But without any positive external feedback your natural motivation will probably die out.

I can relate to the author in many ways, but I didn't take that lesson away from my time in school. In my view, I was born with a natural motivation to invent and analyze things, and my struggle was to find the right environment, with the right people and tools that could grow this motivation rather than killing it with indifference. It's all about meeting the right people who gives you that push.

The author said he didn't need any professor to get started, it's true, but he did need a friend to give him that push, that showed him that at least someone wanted to see him "do it".