I think civic disengagement is a side effect of
1. Massive liberal policy success from 1933-1980.
2. The average American's lack of historical perspective due to social studies instead of actual history being taught in primary schools.
3. Social media spheres of influence funneling people into convenient and "safe spaces" to agree with each other (this includes conservative shitholes like Twitter).
1. The creation of the US middle class and desegregation stems from liberal policies of FDR and following liberal politicians (Ike and even Nixon to some extent). This success has led to people losing the desire for civic engagement as things seemed to be on autopilot in terms of making society better and more fair for most people.
2. Actual history is not taught before college. Instead, it's social studies...little units about short era of history that are heavy on names and dates, and is not what history actually is: connecting time periods and movements from the past to the present. If you don't understand that the US middle class only existed because of big gub'mint, then you're more likely to agree with rich fucks that big gub'mint is bad...because you don't even know how bad things were the last time rich fucks owned and operated the entire government for themselves.
3. No one is stopping anyone else from going to an in-person membership group and debating people who you disagree with. That said, that sounds fucking exhausting, and because things have seemed like they were on autopilot for the first half of my lifetime, let's just let auto-pilot take care of it. Social media engagement is just that. Unless it's used to create physical, meatspace groups, it's just an echo chamber. Yes, that definitely includes Twitter.
So, now would be a good time for people to engage with politics instead of hitting a donate button and voting once every 12-48 months. And meeting in meatspace is probably the best way to start ground-up organizations that will reach the 36% of people who don't participate in elections.
So, who is going to create the group? The Democratic Party? That's not their job, they run campaigns.
So, who is to fault for civic disengagement? Good people who do nothing...but vote and hit the donate button.