I guess others do use that particular technique at times...but it most certainly is used by the left far more against the right than vice versa. Let me state a recent famous example..."George Bush not signing the hate crimes bill...was like my father being dragged all over again." For the Texas NAACP to compare Bush's non-support for a particular hate crimes bill to the dragging murder of a black man by three pieces of trash was a complete joke. So you may be right that the left doesnt enjoy 100% usage of that technique...but its certainly a pet tool they employ much more frequently than the right.
Yeah, but their knee-jerk habit of using the terms "right-wing" and "Nazi" together like a four-syllable word is particularly annoying. To call someone a socialist, statist, left-wing Nazi for wanting to abolish your 2nd Amendment rights is a far cry from calling a Republican a right-wing Nazi for wanting to slow the growth of government.
This reminds me of the legend of Robin Hood. The Marxist interpretation is that Robin Hood's band of merry men stole from the rich to give to the poor. The conservative interpretation is that Robin Hood was about resisting an arrogant state that monopolized the land, overtaxed its populace (although not as much as ours is taxed now, for whatever that's worth), and treated them as subjects with no right to self-protection.