One of the hurdles in helping people/clients with custom themes or plugins is that after uploading once a ZIP, there’s no easy easy to replace with newer versions. Setting up ftp is cumbersome for many and I will never admit I do edits with the Theme/plugin editor. Nope.
On another project outside my domains, a new WP site was set up with this plugin
that makes it easy for me to update theme/plugin code in an ftp-like interface.