While private business certainly is essential, let's not go too far. I can think of ... maybe just one or two pieces of standard computer infrastructure not developed by private business or for profit. Need I list them?
I definitely think that part of Dropbox bet was that the Internet wouldn't develop much in the future. A bet they aren't alone in making.
You mention a bunch of filesystems (some of which with much better scalability than Dropbox), but omit Rsync. Rsync works with any of these filesystems.
The most successful data distribution systems which predate these are from the '90s and before Usenet (esp volume with the binaries) and scene (or FXP). However, the former is mostly public data and the latter is inherently insecure.
Dropbox was nothing special. It was just the first popular one who had a GUI on top of Rsync, and who sold data storage within a package. Its essentially a lucky shot.
WebDAV works great for client-server, but it has a disadvantage: locking works terrible. OwnCloud/NextCloud uses WebDAV, btw.
You might enjoy this talk: https://www.youtube.com/watch?v=PE4gwstWhmc
AFS, NFS, Coda, 9P, WebDAV, SMB/CIFS, FTP, Windows roaming profiles, AFP, etc. were all around and (to varying levels) built into OSes well before Dropbox. Dropbox was a fundamentally different model: files stay on your local machine and get synchronized, instead of living on the network. The entire idea that live synchronization is the correct approach is almost entirely due to Dropbox's success; any OS designer before 2007 would have said "Yes, we have something as basic as a networked filesystem."
If you're objecting to the fact that it takes a commercial venture to explore and develop these sorts of ideas, I too dislike that we're in that place. But it's true. We haven't achieved a way to develop standard computer infrastructure without capitalism, yes; but we've certainly achieved meaningful technology that did not previously exist that's actually working for people.
(And, also, almost all of those protocols I mentioned were developed by profitable businesses like Sun or Transarc or Apple or whomever, and only made non-proprietary at great effort. The ones that started off with public specs, like WebDAV and FTP, were the worst.)