He's not wrong, but a lot of what he says is very dependent on self-discipline. Having a partner, in addition to all of the other perks, also gives you a point of accountability the forces prioritization and a real plan. It is entirely possible to start a business by yourself. People do it successfully every single day but there are a whole lot of complicated factors from financial, legal, technical and psychological…
I think the bigger point is that when widely-respected entrepreneurs like PG automatically rule out those people who "successfully start a business by themselves every day," it can intensify the psychological blocks that prevent many aspiring entrepreneurs from starting in the first place. That means a net loss for everyone.
I've read a lot around this debate, especially on HN. And as someone a month in to their first solo venture, this idea of needing someone to keep you moving and cheer you up has been poisonous to me. I had my first moment the other night, laying in bed, when I realized I hadn't written a whole lot of code that day. I started feeling bad. "Maybe I'm not cut out for this," I thought. Or "this isn't for someone like me."
Luckily, I woke up in the morning and realized I know better. I love what I'm building without anyone telling me to love it. I code without someone telling me to code in the first place. This isn't everyone. But as mentioned in the article, the open source community is just one group of people that can build things without being externally "disciplined."