There are definitely benefits to the 24 hour news cycle, like the Ahmaud Arbery case you mentioned, but I don't think it is clear that those benefits are worth the cost to society as whole. For every case where the outrage is justified, there are cases where there was public outrage that was based on completely false information, or directed to the wrong individual. And this also can motivate people to do things like mass shootings, since you know that the story of what you did will be talked about around the country for days.
Outside of people being targeted for no reason, this news cycle just polarizes the American public. People have their set of news sources that only push them the news supporting their opinion, and spin the news in their favor, moving peoples opinions further to the extremes - politics stops being about real issues, and there is no room for real debate. In a building I lived in they had CNN constantly playing in the games room, and all they ever seemed to have was talking heads discussing Trump, mostly speculation about Russia at the time - does that really lead to anyone being more informed, or cause any positive action? I don't think this cost is worth the few cases where the public outrage was correct and effective.
I think it would be a huge problem if the general public stopped consuming any national/international news at all, since injustice would go unnoticed unless it affected you directly. And of course with things like COVID it is important to be informed about what is going on. But I think we would all be better off if instead of looking at the news every day, we just looked at the top stories once or twice a week on a set of reputable news sites, and stayed out of the comments.