I wonder if this has caught on because the business want's to move fast with new email campaigns and such, but their IT people forbid them from getting a new su

I wonder if this has caught on because the business want's to move fast with new email campaigns and such, but their IT people forbid them from getting a new subdomain? I wouldn't be surprised if in some organisations it's easier to register a new domain than to get any changes made to the "mothership" domain.