This plugin appears to be an excellent option if you’re using the Twenty-seventeen default theme and don’t have the funds to hire a developer or designer to do customization work.
It never occurred to me to package customizer options for a theme into a plugin. I’m not sure why because I do this for custom post types and other theme-specific code snippets all the time.
The customizer is relatively accessible at this point, so I’ve begun using it more and more on my own sites instead of just leaving all the fun for my clients.
And the idea of packaging customizer options in a custom functionality plugin is one I’m definitely stealing.