I think the author is making some huge generalisations here.

"Don’t pick something that needs a pretty UI": What if I'm really skilled in UI dev and have a good visual eye? Or a friend happy to do some free mockups?

"In-person sales are very weird for the developer personality": there is no one developer personality, I wouldn't rule this out at all.

"You don’t want to be going around talking to actual humans.": this is almost never going to work for a startup. Actually talking to people (users, clients, integration partners) is probably the most important thing you can do as a founder.