Certain banks and their services (e.g. wire transfer), as well as payment providers should be treated like public utilities, especially when they have quasi-monopolies. The same for ISPs in areas in which there is only one or two, and other large companies with quasi-monopolies like Google, Apple and Microsoft. I don't think this applies to companies like Reddit or Cloudflare, though, for which there are easy and widely used substitutes.
Because a big reason why I think this is bad is because I thought there are in fact no realistic alternatives to Cloudflare's protection.
If there are alternatives, then I am also in the camp of "okay they can decide who to do business with or not".
But I was under the impression that, if you are a controversial website, at a certain size (not even that big, depending on your enemies) you are likely to draw DDoS attacks of a severity that only Cloudflare can realistically protect against. The DDoS attacks being relatively cheap for whoever orders them.