in the age of monopolies - the whole "it's private" has less and less practical meaning. Is it a violation of 1A? No.
should we be reconsidering laws in an age where all ephemeral discussion is gone and near all discussion or communication or media is now permanent and flows through Google, Amazon, Facebook, and Twitter?
Absolutely. The web was never meant to be so centralized and monopolized. The web has "disrupted" so many industries (ie, flat out destroyed them and then consolidated their functions under one of the main web companies), there's decreasing less alternatives for private platforms.
Censoring speech on private platforms was a really different animal 10 years ago.