Seems entirely legitimate to me that people can choose whatever tools they want to sell the thing they've spent loads of time working on. And in the same way it's also entirely legitimate for you and others to simply choose not to buy.
The advice is simply that it's self-sabotaging to choose the design language of low-value infomercial type websites.
Developers are also a very marketing-averse group.
Tbh my guess is the founder of this product never got feedback from devs before doing that landing page.
The tool could be superb. Kind of doesn't matter. Pattern recognition kicks in.
Maybe they built a great product. If that's so they camouflage its value by making it look like some ebook with a scarcity timer.
You see someone dressed as a hotdog holding a giant promotional "50 OFF, TODAY ONLY!!!" sign outside a restaurant.
Is that restaurant somewhere you'd consider taking a client for fine-dining?
[Edit] - no, obviously not "for fine dining", but jeez, the guy is asking $49, not $4900! Who said anything about fine dining...?!