What he means is that if you're completely ignorant about business, then reading a financial magazine will help you level up over time.
(Related: I've worked with new managers in SV who couldn't define what the words "leadership", "responsibility", "planning" or "accountability" meant, since all they knew was PHP programming.)
It's a good post mortem read.
I gave the same advice about "use case" as in the post mortem to a YC database company a few years ago. The "founders" also thought they were building a better (technical) mousetrap, but I told them nobody was going to pay anything if it did the same as an existing database - it had to do something unique and be cloud-based, like Snowflake, or RDS. They were crestfallen, but still didn't listen to me. I even got hate mail from them before they went under - talk about being clueless to the bitter end.
What RethinkDB did wrong was what was in their post mortem, but also not having experienced DBAs to review the use cases. As a DBA, my default is to say no to new databases, and being the audience, that would have been valuable for them to know.
An example of how DBAs and devs think differently is the Jepsen database reports - devs fetishize those, but DBAs are like, "We already know corner cases aren't going to work most of the time. What's your point exactly?"
Source: experienced DBA.