Phones don't broadcast. A small group of agitators could have used a pirate radio station to call for an attack on the capitol 50 years ago and reach millions of people, which is exactly why pirate radio stations are illegal.
Should we ban every tool that allows you to broadcast? TV, Radio, Tiktok, twitter, youtube, etc? To be fair I think it used to be much much worse when there were only a few broadcast venue, people used to go CRAZY about celebrities, and some shows. It is much better now that conversation and broadcasting takes place on different networks.
The upside of broadcasting is that issues that only minorities experience have been brought to daylight: #metoo, gay marriage, actual insurrections that we should support, demonstrations, health care fight in the US, etc.
Pirate radio stations are illegal because the radio spectrum is finite and without regulation, much of that spectrum would end up jammed and unusable. Pirate radio is illegal for approximately the same reason it’s illegal to drive on the wrong side of the road.
Pirate Radio stations & new LPFM are primarily illegal because Clear Channel/iHeartRadio cannot profit & control the flow of information as well as they do when they have competition. The things Clear Channel hosts, especially on AM, are not even very much different from calling for an attack on the Capitol, having listened to 20+ years (unfortunately) of Rush Limbaugh my grandfather was listening to. You can contact a lot of people on Amateur Radio or CB radio, but it's not illegal because it doesn't compete with big business.