Yes, GT is not 100% waterproof. It's also not breathable like cotton or untreated polyester.
However, the right path IMO is to compare GT to the alternatives, and when you do this it is absolutely clear to me that it's better. More waterproof than very breathable fabrics, more breathable than very waterproof fabrics. The former get you (very) wet from the outside, the latter get you (very) wet from the inside; GT gets you a bit wet from both.
Nobody has made the "perfect" fabric for wet conditions because it likely cannot exist. The fact that GT is not this mythical "perfect" fabric does not, for me, detract very much from it being measurably and experientially superior to the alternatives.
Unfortunately if you read his other writing about Gore-Tex (and waterproof breathable membranes in general), it is clear he does not understand how the technology actually works. He refers constantly to ambient humidity, which is irrelevant, and even gets some facts about humidity wrong.
Cheaper waterproof (not breathable) layers with ventilation (pit zips on jackets and full length zippers on pants) is the way to go. Paying premium for GORE-TEX has not been worth it in my experience.