Part of the problem is the type of Republican Atlas used to attract is exactly ground zero for going NeverTrump/leaving the GOP. If you're a right wing ideologue of the previous era who was thoughtful and read a lot of more theory minded people like Jonah Goldberg and Bill Kristol, you probably followed them right out of the GOP.
Then, for the Trumpers, changing cultural mores. How long would Statesrights, a poster with Confederate stuff in his sig who was openly not cool with blacks or gays, last on the forum now? And yet States was basically an ur-Trumper and I have no doubt he went Trump hard, but despite being one of our top all time posters, he'd not be welcome here now.
Atlas is almost the inverse of real-life situations for me. Here, I find it super easy to fit in. But it was incredibly difficult for me to co-exist with the College Republicans society in my undergrad.
What were the issues you faced with the College Republicans society? I'm assuming it's because you're generally moderate and seem to lean somewhat left on social issues, but I would like to hear more
