As I said before, I believe this all started when Al Gore lost an election after it had already been announced on TV that he'd won. He refused to graciously accept defeat and wanted to be allowed to keep recounting until he got the results he wanted. The Supreme Court slapped that idea down and it's been war ever since.
All the screaming and crying over that heralded a new era of sore loser politics. If you can't beat them, don't accept that, bash them in the media relentlessly day after day after day and make sure nothing they want to do can ever get accomplished. No one's willing to let the other side govern, no one's willing to acknowledge anything good that the other side brought about, no one cares about how everyday people are being affected, the goal is just destroy your opponent. At any and all costs. The internet era with everyone having their own individual 24/7 platform to whine and cry and blame everything bad that happens on the guy they don't like just made things worse.