I kind of feel like the social media/smartphone thing is sometimes perceived as a bigger problem than it actually is. I always see the older generation complain the younger ones are on their phone 24/7. My own experience is, that if you are going out with friends, noone uses their phone (except for maybe showing a funny pic or checking what time it is). And this is the case for basically all people I know.
Of course, there sure are some that are all the time on their phone, even when with friends (especially the so called 'influencers'; but at least they make money with it). But I'd say those are a small percentage, and they are probably addicted, meaning they'd need help. And some addicts and weird people have always existed and will always exist, I doubt that the percentage is any higher than let's say, 50 years ago.
I kind of agree with DNO. I feel like expressing your anger about anything has become very hard to do in the real world - you never know whether someone films you, and the stuff might getting uploaded to the internet, which could destroy your later career. Also, the pc stuff has gotten kind of over-the-top sometimes. And if there is no outlet for anger, it might add up until all the anger bursts out at once (doesn't have to be as bad as a school shooting, but worse than if someone could express their anger in a normal way).
Also, I doubt that shitposting works therapeutic in the long run, I'd say at best it would work short term.