Funny you ask because I literally just got my ham license because of this.

Radio works without infrastructure. Okay there's some ham stuff that is internet-connected et al but overall you are just spewing radio waves into the ether with a variety of simple encodings and someone else can pick them up. So powering a few radios off of a dinky solar panel and battery combo is no biggie, whereas powering cell towers, routing infrastructure, et al is a bunch of generators that need to be fueled and whatnot.

Like... you can hit the 20-meter-and-longer wavelengths with a radio and a random bit of wire and some ingenuity and get your signal all over the place. And the maximum power you are ever allowed is 1500 watts and most folks can make do with far less power than that.

Also, amateur radio has fun stuff to do other than mere EmComm needs. Part of why Twitter used to be handy in a pinch for lesser-disasters in days past was that it could be used for EmComm needs but also had other fun stuff to be done with it. Things that are "just" for EmComm infrastructure tend to get forgotten about and abandoned and rot away to nothingness.

A lot of areas in the US have ARES/RACES orgs to provide an already organized group of people... but some of the fun games that hams play like POTA/SOTA, Field Days, et al also serve to make it fun to have a portable setup.