This is probably even worse now, because only the right-wing ideas and the libs complaining about "both sides" get attention in the mainstream media. Libs have their media ecosystem, as do the conservatives. So an average person will not even hear the unfiltered version of the left-wing idea to begin with, so even if the "both sides are the same" argument is obviously crazy, people don't even get a chance to see what the left-wing version is, they will just have to assume that we believe that the train was derailed by aliens or something. Even if leftwingers have amazing messaging, the default will be "both sides are crazy", while some small group will always be won over to the right, with the left-wing argument not being on offer in the first place.