What I believe it's saying, and accurately so IMO, is there are a lot of so-called "best practices" which are dogmatically followed without stopping to critically think about whether or not they actually make sense in the context in which they're being applied.
My takeaway from "If you don't believe this, I suggest you carefully reexamine your assumptions." is "If you believe something is true, stop and think critically about _why_ you think it's true. Be open to the fact that this process may lead you discover it isn't true after all".