> The result is that software that can be personalized doesn’t need a plugin system or a config file.

Yes, please make me rebuild my software to change an API endpoint or port number. It's a wonderful use of time and electricity to build and spin up agents to fix the inevitable problems with building software. Instead of changing a string in configuration file.

(/s if not obvious).

Configuration and plugin systems exist for a good reason: software should be reconfigurable and modular without requiring the wholesale replacement of the original. Even if the code is open source, there are good reasons to move logic and data out of tree and into config or plugins.