I'd definitely move away from the disposition that it is mostly conservatives that are obsessed with character assassination.
-MSM has brought it to a whole other level with their biased reporting and misinterpretations
(one example was the CNN incident with Sinatra's daughter(Nancy) forbidding Trump to use a song('My Way') during inauguration I believe)... there are others but I'd rather not digress.
But to your question, I think you answered it within your OP; it truly is the quickest and easiest ways to garner support of the masses and discredit a political opponent.
-Honestly, a very small percentage of the population truly pays attention to political issues beyond a superficial level.
--It is much easier to persecute a political opponent for their past indiscretions than to actually research their political standing on each political topic.
'Politics' come along in "seasons" now, in which during this time people pay additional attention to political adverts, debates, etc.
This is a prime opportunity to conduct character assassinations which serve as "cliffnotes" of sorts that help people make knee jerk assessments of political candidates.
--These accusations hardly provide any understanding between the correlation of candidates's stances and what we perceive to be in our best interests.
---You find reasons NOT to vote for someone as opposed to determining why you should.
Can you imagine where we would be if there were no identity politics, there were limited campaign budgets, and detailed debate questions?
-I can't imagine but maybe, a good candidate?