The stack which is required for the Streamified API is really quite large, too. Between node, mongo, elasticsearch, and a few other pieces of software... plus a few dozen node modules and even some custom linux configuration, it's really not feasible to expect devs to install it on their own machines ;)
One could run their own NewsBlur, but Samuel has stated it requires a lot of resources to pull RSS feeds, and so in practice it's much easier to pay them $2/month. (This may not apply if you plan on having business customers who are paying orders of magnitude more than that.) But it alleviates any fear that the service users depend on may disappear; in the worst case, run it yourself.
If you want my opinion, I would recommend finding a small area of your tech stack that you wish was better and starting an opensource project to solve that specific problem. No one expects twitter to give away their source code for their core product, but they do appreciate bootstrap and bower.js a whole lot.