Right. Social media was harnessed by Democrats in 2008 and 2012 to win the elections, by Obama's aides, and staffers. It was seen at the time as revolutionary and catching the Republicans off guard, who relied on the old ways. Part of that was who were the first people on social media? Mostly millennial liberal highly educated from Ivy League and then on down.
When more and more people came onto the platforms, that demo radically shifted, and was used to help elect Trump in 2016.
but to your last point, you can track a lot of trends that start around 2012 when the rise of Facebook and Instagram, and Snap Chat. I can look it up later, but you start seeing anxiety, lonliness, and a continuation of social interactions and community go downward. People lived more and more online, in increasingly insular spaces.
Not to mention the algorithms that keep people living in their own echo chambers, to an absurd level.