That statement was really supposed to be more tongue-in-cheek. Obviously, I know that years of school cannot be replaced by 15 minutes of a YouTube video. For people who just generally want to try writing some simple songs, though, I think it's broken down to be very intuitive.
There's also an argument to be made for how much is good to know and when things will just get in the way. It depends on what someone's goal is. If they just want to be good at a particular instrument, then learning anything and everything will be good. If they want to write memorable, classic songs, then they may end up knowing too much for their own good.
It's why in high school, the band geeks are never in good bands. haha.