> For a Linux user, you can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem. From Windows or Mac, this FTP account could be accessed through built-in software.

(See https://news.ycombinator.com/item?id=8863 )

That comment was written in 2007 when the original suggestion would have been somewhat more acceptable. In 2019, please do not use plaintext FTP for anything at all if you can help it, especially for a setup involving personal documents or other data you care about keeping private. Every single syncing solution worth anything today, open or proprietary – including Dropbox, Google Drive, iCloud Drive, Microsoft OneDrive, Syncthing, et al. – uses TLS or another strong form of transport encryption, and that should also be the absolute minimum bar for anything self-hosted, too.

There are many other better ways of building a Dropbox-like system on Linux these days than that advice, including the aforementioned Syncthing[1], but the appropriate update to that comment alone would be "getting a SSH account, mounting it locally with sshfs[2], and then using Git on the mounted filesystem".

[1]: https://syncthing.net

[2]: https://github.com/libfuse/sshfs

That can get insanely expensive especially wrt bandwidth if you are keeping more than one device synced to it.

Why?