But they have major drawbacks, too. Like: no encryption and authentication. And that means that e.g. critical medical data about a lot of people can be trivially snooped from the airwaves. This is not just hypothetical, it really works, and you can find multiple newspaper articles and reports online on this subject by googling a bit.

Worse, it is trivial to tamper with this and insert forged pager messages. A lot of harm could be done with this, possibly even leading to death of patients.