To call weak EM harmful, you basically have to call everything harmful. Also, it's so important for the modern world the alternative is much worse. I think some of the argument focuses on things like 'do we really need 5g? Why isn't 4g enough. But trying to argue 5g is somehow more harmful runs into the same trap where people are arguing to limit things because they may not be perfectly safe. That says a lot for alcohol, recreational drugs, guns, extreme sports, processed meats, and automobiles, etc.