The argument isn’t a that convincing. Basically, instead of having a good co-founder you could have a bad one. I don’t know enough about the data used to comment on that aspect. Perhaps, statistically, it really is better to found solo. I’m just sharing my personal experience. Having founded solo once, I won’t do it again.
I think the counter argument in the article that was more relevant was the grass is always greener on the other side part. It's hard to form an informed opinion until we've been on both sides.
Though I think it's totally valid to want to try the cofounder approach if you've tried the solo approach and just totally hated it and never want to do it again. I think there are probably also plenty of founders out there who have had a bad cofounder experience and would only consider solo-founding for their next venture.