I have a similar thought, as I rarely become friends with incompetent people. If I were to launch a startup with my friends (that I have worked with over the years) that would be an incredibly competent core of engineers
You have the filter pointed the wrong way. I don't go through a list of friends and filter out people that are incompetent at their jobs, rather the competence filter results in only competent coworkers joining the friends list
People that are competent are more enjoyable to work with, so there is a higher likelihood of us becoming friends.
Incompetent people are annoying and I don't become friends with them