Planning-related. Onsite teams allow first line of management to muddle through many issues in an ad-hoc way: walk over to see if A is stuck, if so go and ask B to help A, etc. This is not good: most engineers hate constant interruptions and best engineers' most productive time can get decimated. But this type of management mostly keeps the ship afloat.

This does not work with remote teams. There, a manager needs to have a longer-term plan, parcel work in a larger chunks, clearly write the tasks and minimal thresholds ("this task is done when you can confirm X"). The manager then sees when someone is blocked, what tasks are getting behind, etc.

This setup is actually better for the worker bees, too, who get clearly identifiable tasks and are not tracked on how they spend their time as long as their task is completed on time.