I think that's a very rigid definition of "lock-in" that implies it must be done with some anti-competitive malice. That's not how I've encountered the term in my past, so I'm welcome to other interpretations.

Per (not authoritative, obviously) wiki:

"In economics, vendor lock-in, also known as proprietary lock-in or customer lock-in, makes a customer dependent on a vendor for products and services, unable to use another vendor without substantial switching costs."

I agree with this. It shouldn't require that the service is purposefully preventing you from changing; lock-in can occur because a service offers advantages that prevent changing by virtue of some other cost.