To be fair, most non-technical users have no clue what FTP is. Twenty years ago, some non-technical people knew, because a lot of downloading was going on involving FTP servers, but that was... well, twenty years ago.

I do not see the benefit of removing FTP. For security concerns, a big warning as with expired TLS certificates would be an acceptable compromise, IMHO.

But as someone who knows what FTP is and still uses it on occasion, I don't think FF dropping FTP support is going to impact me very much.