The owner of the code is then the only person who ever looks at the codebase. This stops code owners from learning from their colleagues, which is the best way to learn at work.
I want to get better at building things, not just some theoretical, fictional app, something tangible that people can use. Something that will be deployed and used in the real world.
Even though you can’t rely on other people to fix your problems, you can and should have a network of people to help.