Why would you ban yourself from interacting with someone who voluntarily chooses provider X or Y or Z for anything?

Because I’m petty

Half the fediverse already runs on servers provided by only 3 companies

I also don’t know those three companies off the top of my head, and while I definitely believe you, I can’t imagine they are anywhere near as big as Cloudflare. If you’re talking about cloud service providers, I’d also consider running an instance that ignores say, AWS instances, but I think that’s a bit different since they don’t specifically provide “activitypub” services afaik. With Cloudflare, it’s much more explicit