chrome and firefox dropped support for it 5 years or so ago, it has had a lot of security issues over the years, was annoying over NAT, and there are better options for secure bulk transfers (sftp, rsync, etc)
Depending on your hardware (SBC), FTP can also be several times faster than SFTP for transferring files over a LAN. Though I'll admit to having used other protocols like torrents for large files that had bad transfers or other issues (low-quality connection issues causing dropped connections, etc).
