Correct. Source: I do low-energy mesh networks. There are loads of tradeoffs, and a lot of it just has to do with the physical medium.

Sure, you could go with an off-the-shelf solution, but those aren't always a good fit for whatever product you're developing. If you can squeeze your bandwidth requirements to an absolute minimum, say, tens of kilobits, you can accomplish absolutely nutty stuff with a cheap LoRa radio and a well-designed antenna. Sure, it's tens of kilobits, but it's tens of kilobits sent and received over a mile between devices with batteries the size of your pinky.