I disagree with everything you said
First Cloudflare is a massive privacy risk, it's absolutely ridiculous you don't see it that way. They measure the speeds users pull data, this alone can doxx nostr users. They browser fingerprint users of websites. What does privacy even mean if they see everything?
https://simplifiedprivacy.com/why-and-what-is-arweb/arweave-website-creator.html
Second, the idea that you need millions of concurrent users is ridiclous. It's the same small bunch of people here on Nostr. Both you and I can not even get 100 reactions if we tried. Nobody cares to DDoS you, or the users using that self-host relay.
Third, there is no purpose in decentralized tools if 2-3 entities control them all. And the only solutions you mentioned are international giants or in your home. You're completely leaving out smaller providers
Let's take your logical thought to the extreme.. if everyone hosted nosflare on cloudflare, then it would be a regular social media site with a single entity. So the only thing magical about Nostr, is those who DON'T use this.