This isn't true in the slightest. Your 'neutrality' or whatever isn't important at all. Every single paper and pamphlet the people writing the first amendment were familiar with was deeply, intrinsically partisan. Those 17th century platforms still expressly retained the right to decide who featured inside their pages.
Neither of those things are owned and moderated by a private company, and private companies definitely don't orient their product on the basis of neutrality.