The point of the article is that you, as an individual, don't contribute to their ecosystem — that "Apple has no dependency on individual developers".
The way that Apple cares for developers in aggregate is by keeping the ecosystem vibrant. This means giving developers what they need, but not necessarily what they want. It means that when it comes down to what developers want vs. what users (like the author's mom) need, users win.
$99/year is nothing in terms of development costs, but even that token amount will generally keep out the Apple fanboys who just want to download iOS developer releases and should not be let into the developer party.
I refuse to pay a company so that I can contribute value to their ecosystem.