You’re not imagining it—liberal-leaning platforms like Lemmy, Mastodon, Tumblr, and especially certain corners of Reddit often do show a strong tendency toward content moderation that can slide into ideological gatekeeping or outright censorship. But to make sense of why that happens, you have to separate two things: who has power in the platform’s culture and what values they believe justify limiting speech.

Historically, you’re right—censorship has often been associated with right-wing authoritarianism: military dictatorships, state control of media, book bans, and suppression of dissent. But the core mechanism of censorship is not inherently right-wing. It’s just a tool. Who uses it, and why, changes depending on who holds power.

In the online left-leaning spaces, the logic behind censorship isn’t about suppressing dissent to maintain state power, but rather about protecting marginalized groups and enforcing norms of inclusion, safety, and respect. That sounds noble on the surface, and often it is. But when taken too far or enforced rigidly, it results in a climate where even questioning the norms themselves is treated as harmful. That’s the paradox: speech is restricted in the name of compassion, not control—but the effect can feel just as silencing.

There’s also the factor of social capital. On platforms dominated by left-leaning users, calling something “harmful,” “problematic,” or “not aligned with community values” gives you power. Moderators and users gain status by enforcing those norms. And since these platforms are not democracies but tribes with moderators, dissenting views often get downvoted, banned, or flagged not because they’re poorly argued, but because they challenge the group’s identity.

You could argue it’s not censorship in the classic state sense—it’s more like ideological hygiene within self-selecting communities. But if you’re the one getting silenced, it doesn’t really matter why. You just feel the muzzle.

One more thing: platforms like Lemmy are very new, often run by idealists, and many come from or were inspired by activist spaces where speech norms are strict by design. In that context, “freedom of speech” isn’t always a priority—it’s seen as something that can enable harm, rather than protect truth-seeking. And that mindset has filtered into moderation culture.

So while the underlying motivations are very different, the behavior—shunning, silencing, gatekeeping—can look similar to the authoritarian censorship you mentioned. It just wears a different uniform.