You can thank BitKeeper for all of this, and Andrew Tridgwell for forcing Linus Torvalds into creating git.
Gits internals can be confusing at first, but once you understand them there's really nothing you can't do. Being distributed by design also helps.
Plus it didn’t have a mechanism to send contributions. I think GitHub “won” because of its web-based PR system.
GitHub is to sourceforge what Facebook was to MySpace. MySpace was first but it was buggy as hell.
Lots of companies were doing Git and Mercurial "forges" at the time. Many of them were better than Github.
Everything was evolving nicely (including Git and Github) until Github used VC money to offer everything for free to blow everybody out in order to lock people into their product (for example--export of anything other than code is still hit or miss on Github).
At which point, everything in the source control space completely collapsed.
If you think SF+CVS is equivalent to GitHub+Git then you never used SF+CVS. Git won because of GitHub, specifically, not because generically it could be hosted on the Internet.
And I definitely think you're wrong. GitHub has managed to get itself conflated with git, and has benefitting hugely from this confusion.
Atomic commits can also easily be moved around (since the repository is a tree of commits with the commits being leaves), and they also make merging simpler in many scenarios.
Larry McVoy was famously wont to engage in trolling upon the Linux Kernel Mailing List, whereupon he did boast of his BitKeeper, which possessed atomic changesets. Concurrently, he did deride Subversion for its lack of the same. Thus, a great drama did ensue, one which ultimately bestowed upon us the creation of git.
git has also succeeded as a DVCS where others have faltered, for various reasons. For there have been monotone, darcs and other such systems; yet, it is chiefly git that has endured.
Subversion definitely has atomic commits. That was it's major advance over CVS.
The major difference between svn and git/hg is svn assumes a centralised repository, whereas git/hg are designed to work as distributed repositories that exchange change sets.
Turns out that you can build sophisticated work flows on top of features they added to support that distributed model - things like PR's. These things are useful even if you have a single centralised monorepositiry of the style svn insists on.
But atomic commits aren't part distributed feature set. You need them in a monorepositiry. After you've experienced your CVS repository being turned into a mess by two people doing a commit at the same time that becomes obvious.
Nope. Subversion made them mainstream:
"An svn commit operation publishes changes to any number of files and directories as a single atomic transaction. In your working copy, you can change files' contents; create, delete, rename, and copy files and directories; and then commit a complete set of changes as an atomic transaction.
By atomic transaction, we mean simply this: either all of the changes happen in the repository, or none of them happens. Subversion tries to retain this atomicity in the face of program crashes, system crashes, network problems, and other users' actions." [0]
[0] https://svnbook.red-bean.com/en/1.5/svn.basic.in-action.html
