What's really funny is how all discussions they host have to be approached from that angle.
So you can't just talk about your favorite TV show. You have to first make a nod to how it features a Jewish conspiracy to push black-white interracial relationships. Only then can you go on to discuss the actual episode.
If people with non-"odious" views end up at such a platform, they will quickly notice the unusual concentration of "odious" views, and generally find it uncomfortable and leave. Thus there is a steady increase in the prevalence of "odious" views until they are near-universal on the platform.
I don't say this to excuse their actions or say that this filter is good, but that seems to be the fundamental mechanism.
And that last part is the entire point: There simply is no mainstream-relevant occurency of left-wing terrorism and murders any more in the Western world. The most relevant militant group was the German RAF, which has all but dissolved in the early 90s (there are three still on the run and occasionally robbing a bank but that's it). In contrast, murders and other organized violence and terrorism based on right-wing ideology is shockingly commonplace.
With online-based hate speech, it is just the same matter, only a different medium - and there is so much more content that draws in right-wing hate speech (such as anti-immigration stuff, antisemitism, Islamophobia and LGBT hate) than anything that inspires left-wing hate speech. The only thing that comes close to hate speech from the left wing are the "eat the rich" slogan and Stalin/Gulag memes, and that's it.
As a result, it is obvious from the numbers that the right wing will always complain about "we are getting censored and the lefties are not!!!"... well, duh, how about if the complainers would stop doing the things they get moderated for?!
Those whose focus is overtly offensive and oppressive speech, however ...
Reddit claimed free speech as a value in its early years. That sentiment has evolved, for all the usual reasons.[1]
It is possible to host a wide range of significant views without becoming overtly hostile to the majority of the population, and the viewpoints held by those.
Reddit was in no way "the original free speech platform".
________________________________
Notes:
1. TL;DR: it's untenable and spirals into a cesspit, QED.
My main complaint with Reddit is that the direction it's been taking the site over the past five years or so, and more pointedly the improvements it's not made, are far divorced from where I'd like to see it go.
Reddit wastes my time and does not reward time spent on site with valuable insights. Not strictly for cultivating misinformation and disinformation, though that's a fair-sized piece of my concern. I'm more concerned that it simply kills good conversation or prevents it from arising in the first place.
I can't really blame them for not stepping up to the plate and saying 'fuck off', since the genesis of the site had to do with Reddit overmoderation, and even appearing to step into the same shoes could have had killed the site.