The point of the article is not clear to me. What is the relation between "start with why" and "databases are becoming a commodity"?

It is true that having a unique idea for a startup is no longer (if it ever was) sufficient since it will be copied almost instantaneously by another company, that may actually do it better than the original startup. In the hardware area, this is absolutely true. Any decent-selling product on Amazon is guaranteed to have Chinese copies within a matter of days/weeks.

Also, I think databases were always a commodity. About 40 years ago in a developing country, I was using dBase & FoxPro (obtained free) as a database for my father's business. Today's databases are a lot more sophisticated, but commoditization is not new.