Editing a config over SSH means nano or vim
You need to change one line. Instead you are in a terminal editor with no syntax colours, no usable search, and shortcuts you look up every time because you only do this once a month.
What it does. The file opens in a real editor with highlighting, line numbers, find and replace and word wrap, so a one-line change takes seconds and you can see the structure of what you are editing.
A dropped connection truncates the file you were editing
The failure mode people actually report with SFTP tools: the save appears to succeed, or the connection dies mid-write, and the file on the server is now empty or half written. On a vhost or a systemd unit, that is an outage.
What it does. Nothing is ever written in place. The new content goes to a temporary file beside the target, is read back and checked against a SHA-256 of what was sent, and only then atomically replaces the original. A failure at any step leaves the original exactly as it was.
Editing from Windows breaks shell scripts
A Windows client saving CRLF line endings into a Linux shell script produces the classic "/bin/bash^M: bad interpreter". The file looks fine and will not run.
What it does. Line endings and text encoding are detected when the file opens, preserved on save, and shown in the status bar. A file authored on Linux does not acquire carriage returns because you edited it from a Windows desktop.
Someone else changed the file while you had it open
A deploy ran, logrotate fired, or another admin was in the same file. A normal editor saves over it and the other change is gone with no trace.
What it does. The timestamp is recorded when the file opens and checked again immediately before writing. If it moved, the save stops and tells you, rather than quietly winning.
Finding the right file across the server
The setting is in a config somewhere, you do not remember which, and grep across the box means recalling the flags and reading a wall of output.
What it does. Search a folder or the whole server for a filename or a line of text, and open the match straight in the editor.