Widely used? By whom? Devs who don't understand rsync or scp? Give me a practical scenario where a box is running FTP but not SSH.
Edit: then account for the fact that this rare breed of content uploader doesn't use an FTP client... there's absolutely no reason to have FTP client code in a browser. It's an attack surface that is utterly unnecessary.
People who navigate ftp storage maybe? Like Linux repos?
Linking to an FTP file from a web page.
Also, the protocol is pretty much a holdover from the earliest days, before encryption, or complicated NATs. I remember using it with just telnet a few times. It's pretty cool, but absolutely nobody should be using FTP these days. I remember saying this back in the 2005, and here we are 20 years later, someone still lamenting dropping FTP support from a browser? I think we're decades overdue.