One big difference is that Obama isn't and wasn't a total bad person bad person
I’ll concede (as I did in my remarkable thesis), that part of the problem is that Trump deliberately trolls liberals more than Obama did. That’s a fair and accurate point. But Obama is himself a pretty terrible person, a real jerk to conservatives, and his policies obviously rankled conservatives. We did not melt down nearly as hard as what we’re witnessing.
And it’s not just the meltdown, but what the meltdown looks like! The liberals have fallen to the most visceral of reactions. With some exceptions, there’s very little reasoned argument. It’s largely just crude epithets, screaming, and violence at this point.