Non technical people won't use Docker, it's too complicated. Unless you make some environment as easy and widespread as your typical CPANEL shared hosting, you won't compete with PHP for that kind of end-user.
Can I download your non-PHP app, copy and paste into a folder, and get it running after 5 clicks? More important, are the majority of apps of non PHP langs like this?
Most PHP apps out there are dump easy to use. That's not the case even for Python.
Don't get me wrong, as a developer I hate the bloat, but as a UX/UI PoV you can install a lot of shit that's dockerized pretty easily...
sandstorm.io is a cool way to self-host open source projects for example