This can be significantly better than walkie-talkies. In poor reception, sometimes you can't manage to deliver even a simple message coherently (especially since, to be understood by a fellow human, you need reliable communication in real time for the duration of your entire message).

But usually, you just want to get a message across. You want something like morse code, not voice. Delivering a short textual message, not in real-time but "instantly", with redundancy, error correction and retries, serves me better than walkie talkies.

(Heck, you can deliver a short audio fragment, but I don't see too many people using the "send voice" feature in Whatsapp, don't know about you.)