Very surprised by this remark, what is your source for this kind of information.?
Spotify was a community plugin. When Spotify pulled the plug on the used API and no-one wanted to redesign the plugin, Volumio stepped in (took the responsibility) to fill the gap, even though there was no resource available to do so.
The plugin is working when used from the Volumio UI, the connect function is yet not as it supposed to be, which is known by the development team
So give them some slack