What hasn't changed over the last several hundred (many thousand) years is basic humanness. Part of that is a variable ability to cope with stresses. Some people manage coping very well, others not. There are mental illnesses that apparently arise without excess stress, coped with or not, like schizophrenia and bipolar. Migraine and epilepsy have long histories. Intelligence varies now and has varied in the past.
I think we can assume that there has been a more or less constant level of mental dysfunction. It may not have been recognized (or recognized as something else), and may have been more or less debilitating.
I find most social media to be tedious and annoying. I don't like to have information 'pushed' at me; I don't like the chaotic sharing of significant, trivial, and often enough completely false and misleading information.
Social media applications are designed to engage -- and keep users engaged -- for extended periods of time. It supplies rewards; new posts generate just enough pleasure/stimulation to keep you on site. A "sort of addiction" develops. That is slightly true even for The Philosophy Forum. One continues to use static sites (like dictionary or encyclopedia sites) because they supply a certain kind of service, but they aren't "addicting" to 99.999% of the population.
What social media and advertising are particularly good at is arousing us, to a greater or lesser degree. The arousal doesn't have to be pleasant or positive -- it can involve irritation, cognitive dissonance, strong disagreement, disgust, embarrassment, anger... all sorts of reactions.
Some people become over stimulated, excessively aroused, and so on. Excessive arousal and over stimulation over a long period of time are unhealthy and very wearing. Outright false information (Donald Trump won the 2020 presidential election) is believed by some share o the social media audience and can lead to social conflict. People who believe Trump won, that Covid 19 was a fraud, that vaccinations are very dangerous, and so on may run into a lot of friction when they air their false beliefs.
People whose base line mental status isn't all that stable to start with can end up much worse off from engaging in too much social media.