Oh yes. And even disregarding tenure, you have cases like illness (see e.g. the Word 1.0 postmortem, page 14, talking about losing a key developer), or people changing project.
One time, I inherited a big steaming pile of spaghetti my co-worker wrote to meet a tight deadline, before being shifted to another project. That code implemented one of the key functions of the application, and half a year later, the customer demanded extensive changes. Believe me, I would have paid half my monthly salary the just to have a third of the comments that we see in this Kubernetes file.