Hard agree. The only case where "You fix all your own bugs" makes sense is a small company or start-up... but it's also a bad idea. Every engineer should get up to speed on every feature until it is no longer feasible/reasonable to do so.

We intentionally cross-train and work bugs in "others code" (we do not assign code ownership, after I review and it is merged, it's is my code now, for as long as I work here lol).