I think the sphere of technology where he's focused (frontend) is particularly fast moving right now. It is extremely humbling to read about somebody like this feeling this way. I know many developers, myself included, experience these pangs of inadequacy on a frequent basis. It would be hard not to, things move fast and everyone around us is talented and smart. But, just like anyone else, I think this article reminds us that we're all human, no matter how talented, and open to feeling inadequate. There's always more to know, more to achieve. But its good to pause and focus on the skills we have sometimes to be grateful for what we've done.