Why should social media companies be protected from legal responsibility?

Probably because they are super-rich and have bribed .. I mean contributed to campaign funds of many politicians and their politicians wrote the laws to let them off.  Personally I think they should be liable.

No they should ne sued for any fake news and political bias.

Because newspapers have advance editorial control.

Social media sites do not.

Duh.

Now, if you would like social media sites to work with advance editorial control, that would means that EVERY time you want to post something to, say, Facebook, or Tweet something out, your post or Tweet will NOT go out until an editor reads it, and OK's it.

Which, given how many people want to post to either site, could mean wait times of days, if not weeks. Would you be OK with that for your posts or Tweets ?

They effectively are classed as utilities in law, They are classed as a platform but act as a left wing publisher.  Trump was quite right to try and adjust their legal status.