The tech is certainly very weird, but it's not actually unreasonable for the society as presented. I think the implication has always been that while they have a lot of modern technology, what they don't have is the global infrastructure needed for something like the internet; they have no satellite technology at all, in fact.

So any phone or telegram communications between villages would require a direct, physical line between areas. These would be very easily sabotaged, and just as easily tapped and subverted during wartime (which…there have been 4 World Wars in the span of TWO GENERATIONS).

Meanwhile, a supernaturally fast and well trained carrier bird is SIGNIFCIANTLY harder to deal with comparatively.

Kishimoto, IMO, doesn't get enough credit for his worldbuilding with Naruto. None of this is explicitly stated, of course, but a lot of things can be inferred from the text in a logical fashion, without ever needing to BE explicitly stated; it just makes sense.

"Edit:" The exception is radio technology (which they use multiple times over the course of the series), but that has some pretty strict range limitations (which the series also addresses).