You really don't want a completely unregulated wild west that we would see if they could not moderate their platforms. It may also require identities to be verified (and reduction in privacy) to address civil damages (defamation, etc.). If we removed the safe harbour, these platforms would just shut down commenting as the liability is unacceptable.Many disagree.
They should only be granted immunity if it is in the public interest for them to have it.
I think you're only okay with them having both immunity and the ability to censor viewpoints they disagree with is because you generally align with their views. If you disagreed with them, you'd likely think differently.
The political bias in these companies and their policies is very well documented.