1/ ext3 is the only filesystem I know of that forces and fsync before committing a rename.
2/ ext3 is about 10 years old, so it hasn't been around for "decades" unless you mean "0.9 decades".
3/ When rename was first introduced into Unix in the BSD, it was atomic in the sense that even in the event of a crash there would always be a file with the destination name, either the original or the new. This is in contrast to the previous behaviour. which required:
- create "file.tmp"
- unlink "file"
- link "file.tmp" to "file"
- unlink "file.tmp"
which can easily leave nothing called "file". This is all that "atomic rename" means, or at least all it meant before ext3 gave rename unfortunate (though useful) semantics.
Though I cannot know the intention of the author of that post you linked to, there is no prima-face reason to believe they mean anything more than the atomicity of names (not of contents) that rename has always had in Unix.
(and half-written files are easy to detect by writing a checksum at the end. If you suffix each file with a timestamp it is easy to know which is the most recent. And file older than a few minutes will be safe-on-disk so you are always free to clean up any file older than the youngest file that is older than a few minutes)