There are plenty of sound sleepers for whom a smartphone isn't loud enough to wake them up, and many others who simply prefer a single-function device that's always there, always works, and never needs recharging or updating.
Since I moved into my current house almost six years ago, I have not plugged in, let alone turned on, a single radio. All of my listening in the house is via either smartphone, tablet, Roku, or Amazon Echo. I also set the alarm on my Amazon Echo to wake me up at the same time each workday morning. I have a backup on my Apple Watch just-in-case my internet or power goes out, but that's only been a problem once. My neighborhood's power lines are underground. So, unless something happens to a feeder line, at the power station, at a transformer, or someone crashes into the box outside my house, I have little to worry about. I guess I could also forget to pay my bill, but they usually give you plenty of notice before they disconnect for nonpayment!
At my previous house, I usually woke up to the alarm clock, but, even in the time I've lived at my current address, I've noticed smartphone apps have improved dramatically as alarms. Even five years ago, they could be unreliable on your iPhone. In fact, as recently as three years ago, I had iPhone apps with unreliable alarms. iHeartRadio seems to have gotten rid of its alarm capability, though it still offers a sleep timer. Of course, with iHeart stations being available on TuneIn now, I can just use TuneIn if I want to wake up to an iHeart station when traveling. TuneIn is reliable and has its own buzzer as a back up if your internet goes out. Audacy seems to work well now, too, though, I've noticed it can have problems on hotel WiFi. That's probably more a function of the hotel WiFi than it is of Audacy, but the backup alarm has never seemed to work quite right for me.