I think the blame is displaced. It’s not these nice companies that decide what you are and what you are allowed to see. It’s you. Or more generally - we, the People, ourselves.
Indeed: Gab is not using Amazon or Google cloud services, Visa and Mastercard do not serve Gab - it has to rely on checks, money orders and crypto. Gab does not have an app… actually it has, in a way of a web link, copied to your home page - btw I have never seen an app that was better than a web page for the same company, have you? Gab has even launched GabPay, its own payment processor open to others. Gab explicitly promise not to delete anything unless it is found illegal by a court.
Still, you the People are not using Gab, you are using Facebook, Twitter and Tumblr. Why are you not using Gab? Last time I’ve checked it was because Gab… does not delete the content that you the People find objectionable!
A cherry on this cake was the decision of some state GOP party committee to delete their Gab account because Gab refuses to censor anti-Semitic content.
So, please - do not blame this nice long list of the evil companies. You have at least one alternative. You, the freest people in the world, are not using it. Not enough censorship there.