The examples all only show Zips but you can apparently add in EXEs, MSIs, DMGs, etc. I'd wager that they won't put up with high numbers of downloads on free projects ala FileZilla, GIMP, PortableApps.com on SourceForge, though.
Except that bandwidth is not actually free. Setting up on a high quality network of mirror servers around the world is usually ~$50 per TB (on something like MaxCDN that we use) but more like $100+ per TB on something like Akamai. That's buying commercial bandwidth on server networks. I mention that as SourceForge has a worldwide network of servers they get from all sorts of companies in exchange for advertising and that we can use for free.
We could setup on something like an unmetered host. We'd lose the worldwide network and geographic closeness of the servers to the downloaders, of course. You can get a 1gbps dedicated unmetered connection for around $800+ a month (not including the actual server) at several providers. A 100mbps dedicated unmetered would not be sufficient for PortableApps.com as it would only total 20TB a month used fulltime (of the theoretical ~32GB max it could push if you discount overhead, etc).
GitHub is a developer tool. Users not interested in viewing/changing/building the source code should get the software from the project's website.
[1] https://github.com/blog/1302