It's important not to start using a service which will be difficult to cease using. This is how lock in occurs. It's not truly convenient if you're stuck with it.
That's a bit extreme. I would say that it's only inconvenient if you need/want to switch - everyone can make a guess about the probability that they will want to switch in the future, what effort it would take and whether that's worth it for the value they will get in the meantime.
she either calls or messages, which from the lock-in standpoint is just better and perfectly adequate - it means much less spurious messaging