Here's the thing. First of all, people are dismissing because so far it seems like it's about his son and crass. It's not dismissing that it's shady, shitty, and sad to see. It's dismissing the "This proves Biden is X".
In regards to Trump prior, it probably has just as much to do with that he literally asked Russia to hack, then they hacked, and then he got caught doing about 400 shady things. Least of which is kowtowing to Putin, a man he still will not say one solitary non-positive thing about. But all that aside, yeah, the left is waaaaaaay too into the Russia stuff. It's a huge problem both that they are obsessed with it and that it's probably true. Because, let's be honest, we just found out Trump has a Bank Account in China, and nobody really cared. They didn't care because they either already knew he was corrupt and shady or they refuse to care. The dealing with Saudi Arabia (you know, the 9/11 guys) also really shitty. But you either already knew that or already didn't care.
Anyway, everyone has picked their side outside of some of the older middle-america unconnected lot. And they're going to usually be dual-issue voters that also look at character.