There are lots of quality of life improvements handling phone this way. For instance, I have a phone number I’ve had for 20-odd years at this point. I receive something like 3-5 unsolicited calls per day and a few unsolicited SMS a week at that number. It must be in every spammer/scammer database on Earth at this point. However, since I’ve had this number so long and given it to so many people, I want to keep it.

Many XMPP clients give you pretty good control over blocking; you also have the ability, if you want to write some code, to block arbitrary patterns of phone numbers. And since it’s all handled in one app, you can block calls and SMS/MMS messages from a phone number in one place. All of that has meant an improvement in my life–I can keep this old number, and even though spam gets through sometimes I have a much easier way to deal with it than text clients and dialers on Android give you.