A few early companies failing to find product-market fit before the money runs out doesn't prove anything, other than that early stage startup investing is hard.

Webvan and Pets.com were held up as proof that e-commerce couldn't work at all because nobody wanted it. What really happened is that we now have e-commerce at a scale that WebVan and Pets.com couldn't even dream of.

Pets.com now goes to PetSmart.com which does basically what Pets.com was trying to do and has a successful business out of it.

If your point is "some early investors will lose their money" then I agree wholeheartedly. That's not a novel claim, though. It's also not what the blog post is arguing.