I think underlying Kent’s statement is an observation that is undeniably true. The closer a test is to the actual way the software will be used, the better it is in a number of ways, _all else being equal_. All else is never fully equal, which is why everything is about tradeoffs.
But when a test aligns with how the software will be used, there are a whole bunch of synergies and benefits. Simplicity increases, clarity increases, you start getting multiple payoffs for each bit of effort you invest.
I’m sure people cargo cult it and lose track of the tradeoffs, like anything else, but there’s a solid point under there. And I agree with him, it is valuable enough to be called a “best practice.”