Maybe the other person enjoys being on the phone and hearing your voice.

phone calls (POTS voice) are better than text, thats not only my opinion, but also for those on the receiving end of the call

The point is showing you're there for the person, giving them the opportunity to mention something that's on their mind. It's about showing a special sense of availability, contrary to the texting availability that you provide to anyone else on God's green earth that may have your phone number saved or written down somewhere.

texting isn't ideal because you might get a response in an hour, or two days, or the next minute.

there's a lot of value in being fully present for a social interaction: when you're on the phone and paying attention, it's typically a lot more engaging than the other person watching a video, texting 4 other people at the same time, or whatever else people do in between texts.