Ask HN: Team structure: Specialists vs. Generalists?

When structuring a team - of software engineers in my case, but it could apply equally to other disciplines - what are the pros and cons of having team members each “own” specific parts of the code base versus share responsibility equally? To be clear, I’m assuming the software organisation is already broken down into teams of ~5-15 developers.

I’d be interested to hear peoples experiences of both approaches. What circumstances might come in to play here and make one approach preferable?