It's not that it's that complex to need all of this. It's about ease of use. Home Assistant OS makes life simpler for users (such as myself), it makes it easy to use adding that run as additional docker containers, it makes plugging in USB z-wave/zigbee devices a breeze.

While it is technically no longer supported, you can still install the whole kit and caboodle using pip in a Python virtual environment, but why would you?