Another way to read this, which the author indirectly touches on in his listing of expired domain auction results, is the $$$ value of the domain itself.
It's kind of insurance for the situation where your side project/business either fails to materialize or goes nowhere. A solid domain should at least retain its value so you can view the perceived authority/trust as free (or a dividend) on the initial investment in the domain.
This is the basis I've been using for some of the prospective side-projects I've been mulling. I've been buying some decent domains as investments both in the domains themselves and the value they would bring to my projects.
Here's a specific example:
I've got a few ideas related to energy, eg. a system that'll let IoT devices/smart appliances/software base decisions on the cost and environmental impact of the energy required for an application. So I bought http://energy.io as the eventual home for this. It carries the authority/trust that the author describes, at least as a developer-focused business, and in the worst case I'm sure I can resell it for an amount comparable to what I paid.