This isn't an idea. It is a constitutional fact, one that is self-evident by reading the amendment.
> I can want companies to abide by this value.
Sure. Want away. I support your right to want things.
> When a social media giant is so large that governments use it as a communication platform, maybe it's a town square now?
Different things are mashed here. Public square implies public (Gov owned) property. A Gov official that posts a comment on my blog wouldn't transform my blog into a Gov owned entity. It would be a disaster if it did because it would become trivial for any Gov offical to seize my entire blog.
> (The 1A protects private entities from Govs.) Unless you're a baker.
I have friends who work at banks. None have mentioned that their 1A rights are being violated by any government. Should I ask them directly?