I want to say this up front and get it out of the way: I went to HS in the Sugar Land area, and at the time it was hardcore Republican (our Representative was Tom DeLay). Parents were Republicans, I was a Republican all through the 90s (George H. W. was my first Presidential vote), but not hardcore - I didn't care what Clinton did, other than if it required me to be deployed overseas. Surrounded by Republicans at various jobs, in the Army, and even in college (but did not go down the College Republican rabbit hole). Heard way too many hours of Rush Limbaugh (but wasn't whipped up by him, more entertained than anything) When it was clear that George W. was running for the WH, I had friends convince me to join the campaign as a volunteer and then paid worker, with the view that I could use that to get a job outside of the tech industry (I ultimately bailed on that, as I found a tech job I was happy at and had gotten married). I'm not going to rehash everything, but I bailed on Bush and the Republicans for the most part by the time 2004 rolled around. Iraq was a huge issue for me and one that I could not overcome. Palin as VP choice in 2008 was probably the last straw.
I had voted for the occasional Democrat for one reason or another, voted for plenty of Libertarians and Constitution Party types, but prior to 2016, really didn't vote for more than a handful of Democrats. The result is that outside of a few relatives and (more and more) friends, and liberals here on Surly, I don't have a solid grasp on Democrats at large.
So no, I can't definitively talk about whether both groups engage in this behavior, as I have never actually been a part of a full-blown liberal group or immersed myself in such a campaign, or have spent years only voting for (D).
But in my time as a Republican for over a decade, and in my time working for W's campaign, I never saw the wide spread nastiness that I saw in 2016 through now. I was aware of the rumors that Rove was trying to destroy McCain with the "McCain has a black baby" rumors, but I also knew about the rumors (and some of the truths) that other candidates were trying to bring W down with in the primaries. I'm now well aware of Newt's war against the Clintons, much more aware than I was then - I was more concerned with getting laid and getting paid than who Bill was banging or Hillary was executing, but in hindsight, that feels more like a vendetta against the Clintons than anything, and feels more "localized".
I do know that I didn't see George W spend his press conferences pushing personal vendettas against the Democrats and he wasn't going around to rallies getting people to chant "Lock him (Al Gore or Kerry or Bill) up!" and supporting groups that believed the liberals were literally demon-possessed. For all of his faults, I didn't see George W embracing the batshittery coming out of the Alex Jones camp (and in fact Jones despised Bush). I didn't see Obama going around to rallies, to cheers of "Lock McCain up again!" or "Lock Mitt up!", and he didn't spend his time embracing batshit extremist movements that believed Republicans were cannibalistic humanoid underground pedophiles (CHAPs) that were living off of the blood of children.
I didn't see Bush or Obama cheer on people at rallies who wanted their political opponents locked up (or worse), or talk about beating up liberals or conservatives in the crowd.
But over the last 4 years, I've watched Donald Trump constantly trash Democrats at press conferences, at rallies, on twitter. I've seen him embrace groups that believe liberals are cannibalistic pedophiles, and that believe he is going to round up his enemies and execute them on the steps of the Capitol or wherever. I've seen him constantly cheer on people who want his political opponents locked up.
I have seen Trump deliberately spread misinformation about things, simply because liberals embraced whatever it was, including misinformation about covid, that could harm or even killed his followers.
I have seen Trump encourage his followers to "liberate" states like Michigan, that had liberal leaders.
And prior to 2016, I saw Trump try and do everything possible to make his fans believe that Obama was not a legitimate President and American.
And it all culminated in January 6th.
George H. W., Bill Clinton, George W. and Obama never went so hard in the paint in trying to trash people with different ideologies. Not even Newt at his worst in the 90s was trying to sow chaos on such a widespread level.
And the GOP as a whole is still refusing to disavow the worst of what Trump said and did. And for all of their faults, CNN, CNBC, MSNBC, etc. don't devote their entire evening blocks to just trashing the shit out of anybody who doesn't have a liberal viewpoint, unlike Fox News who has embraced and pushed the idea that liberals are literally destroying the country and won't be happy until the Russians or Chinese or whoever take over.