This is a really great question. It's not an insurmountable problem, but the compromises need to be understood.
Further, there are lots of things that can be done on the receiver side to smooth out the experience. It is frustrating for customers when a product hasn't thought about how imported content will perform. Often you are left with problems like any edits to the import needing additional fields completed to edit (possibly a significant cost per edit), content can't be fully rendered so appears as an HTML blob in a field, imported data can't be filtered so you can't easily hire someone to fix it without fishing through other data etc.
If you are entering a mature market then importing a competitor's content in a streamlined fashion is a great way to gain adoption and lock in customers. Some markets have lots of competition so you can possibly only target smooth migration of a subset. It shouldn't be an afterthought.
Further, there are lots of things that can be done on the receiver side to smooth out the experience. It is frustrating for customers when a product hasn't thought about how imported content will perform. Often you are left with problems like any edits to the import needing additional fields completed to edit (possibly a significant cost per edit), content can't be fully rendered so appears as an HTML blob in a field, imported data can't be filtered so you can't easily hire someone to fix it without fishing through other data etc.
If you are entering a mature market then importing a competitor's content in a streamlined fashion is a great way to gain adoption and lock in customers. Some markets have lots of competition so you can possibly only target smooth migration of a subset. It shouldn't be an afterthought.