My real question is, however, who owns the servers? Landing page stattes it uses blockchain, which wakes up my internal BS detector. Could the author elaborate? added missing verb
Anyone can operate a Skynet Webportal (the server), and Webportals can choose how they'd like to monetize – for example, they can run ads.
You can also run your own Skynet Portal by downloading Sia v1.4.3, released today. It costs about $10/mo to run a Portal because you have to form file contracts with a few hundred storage providers on the network. But then you do not have to go through a Webportal middleman.
Disclaimer: I work on the Sia/Skynet team.