I remember this too, but the second point is the crux of the usability and lock in. It kind of relies on another product having an importer to ingest it to another product/service. Or you have to pay a consultant to do this for you (write a converter and run it to do the import). Either way it does introduce some friction to leaving and using another service.

There's also the idea that if you provide an easy way to exit the service then people are much more likely to buy the service. Since they know they can easily get out of it if they don't like it.