A model where "one person defines how it works", is a closed source model.
I didn't know the Linux kernel was closed source

It's been open source since day one. And Linus has been defining how it should work since
1994. This doesn't prevent lots of unofficial patches, forks,.. though as well as lots of official fixes, patches,.. That were contributed by how many devs ? A hundred ? Yet, only one person decides. This wouldn't have been possible if it had been closed source...
You may decide and stay opened... At least outside of the Amiga circle. I'm not sure this is possible here: most open source projects lack direction/guidance. And lots of people still deciding would rather see their software die rather than risking loosing control and.. Ownership.