It sounds like your criticism is about their product, not about their business model.

The business model of having a popular product with great documentation, which leads free users to additional paid services, seems like a very valid business model.

Even the criticism you have for their product is along the lines of "the product only worked because they identified a problem in the market; If someone else identified it, this product wouldn't even be needed!". Which is, well, true, but also true for almost any other successful product.