In the same way that there is a small but key difference between victim-blaming and stating that precautions can help thwart crime (i.e., “If you lock car doors, car is less likely to be stolen”) I think there is a small but key difference between the “tone-policing” that is attacked these days, and people who are trying to say that Message X would be delivered much more effectively if it were communicated a different way (i.e., “A peaceful protest would be effective, but blocking the highway actually turns public opinion against your cause.”)
But increasingly people trying to suggest a more effective method of communication are being shouted down as “tone-policers,” and I think the main difference between the two is that tone-policing is what your opponents do to you while suggestions-for-more-effective-communication is what your allies do.
“Tone policing” IMHO, is based off of dis-ingenuity - namely, that you do not want to hear what the opposing side has to say, and so you lecture them to be more polite or quieter about it, with the real motive of just wanting them to be quiet altogether. But among some circles today it seems like even folks who point out “Spraying graffiti and vandalizing the neighborhood properties caused support for your cause to plummet” are being painted with a broad brush and an overall label as “tone-policers.”