I don't find myself disagreeing with anything they said.
But I think the key reason open source persists, is its availability. Even if it's not the best software, it's available in 5 years, in 10 years, and 15 years. So many companies outcompete open source projects, and then die on the vine, and disappear. They never get to actually compete in the evolution of the software.
For all of open source's faults, it's available, so it can evolve over time, it is persistent.