The point is that there are lots of failed oss projects. Further, a startup has a lot more requirements than an oss hobby project. For your hobby you can send an email to a listserv and say “burned out, taking a three month break” or you can focus exclusively on the code.
But a startup needs to make money or it can’t pay people. You don’t just need code. You need a product and you need to sell it.
A lot of the Apache projects came from companies. Although some of these were more like one person at the company developed it and the company funded and maintained it.
Did Kubernetes start in person as in in the same room? It was built by multiple people but I don't know if they shared an office space. I thought it was that they shared a building.
All of the other ones though are pretty solid examples of team-driven OSS work.