Sure, there's no accounting for preferences. But for many, a voice call taking the place of every text conversation is a lot _more_ intrusive (albeit in a time-limited, focused way). Shooting off a couple of texts to nail down the details of when you're meeting up for prearranged plans is convenient for calls because it doesn't have to be fully synchronous: send the text, and if the other person responds when you're free, then you can have a synchronous conversation. There's no real analogue with phone conversations other than playing phone tag, which seems like a lot more mental load.