Because the level of mischief between republicans and democrats is just not comparable when objectively assessed (let's say from a historians perspective).
To give you an example from another context which is similar:
In Germany, polticians and some news media have started to use the notion that right-wing terror (e.g. neo-nazi) and left wing terror (e.g. Antifa) are equally evil. If you look objectively though, there is still a disproportionate amount of right-wing terror and many of the crimes attributed to the left-wing are really just part of their fight against the right (they are anti-fascists for a reason). While right-wing terror killed German citizens and immigrants each year, there is no comparable level of crime anymore that could be attributed to the left (need to go back 40 years).
I would like to see the numbers that support this for the Republican/Democrat version of this story. I feel like most people would have strong confirmation bias when assessing this topic.
Also, do you have numbers for looking at this from the perspective of the politicians? My comment was mainly focused on the politicians and party leadership, not really on individuals without an official capacity.
To give you an example from another context which is similar:
In Germany, polticians and some news media have started to use the notion that right-wing terror (e.g. neo-nazi) and left wing terror (e.g. Antifa) are equally evil. If you look objectively though, there is still a disproportionate amount of right-wing terror and many of the crimes attributed to the left-wing are really just part of their fight against the right (they are anti-fascists for a reason). While right-wing terror killed German citizens and immigrants each year, there is no comparable level of crime anymore that could be attributed to the left (need to go back 40 years).