My dude, I think you're not super familiar with these technologies.
The most basic form of a content delivery network is a set of globally distributed servers that replicate content from a source of truth and a network to direct traffic to the closest server with a valid replica. So the cost here is servers.
With Lemmy, this problem is solved by eliminating the need for individuals to own many servers and a lack of need for trust between servers. The effort and cost is distributed among individual humans, making it manageable.
Now, if you're familiar with blockchain, you probably perked up when you heard "lack of need for trust." That's what the blockchain was built for! Perfect fit, right? Ehh, not so much.
There's two problems: acting as a proxy for content requires trust, and some single service needs to direct clients to the right local server. If I can arbitrarily join some network of serving content, I can always tell other servers in the network that I'm serving what they ask... and then serve ads. There's no (reasonable and fast) way for the network to verify that I'm serving the correct content to every client. There's no way to avoid the need for trust. Additionally, DNS, which directs you from mysite.com to 120.1.2.1, isn't intelligent. It can't direct clients to a geographically (or route-efficient, fucking ISPs) local IP. The best it can do is pick a random one from the pool. So when you go to lemmy.world, DNS can't pick the correct server for you. So some set of servers needs to do the logic to select which local server to actually get content from. Those servers need to be central for the whole content delivery network.
This company you linked is just another company using "blockchain" to get investment money. If you read through their page to get a cursory understanding of how things work, an easy question comes up: what is the purpose of media
tokens? Sure, maybe you can buy CDN time with it, but when you pay that token to someone providing compute... what do they do with that token? It's worthless, just like crypto currency. Fucking scams. All that said, blockchain is a super, super interesting technology. There's just very, very few suitable applications of it.
I've worked in IT for about 12 years now. Everything from infrastructure monitoring to data analysis to data engineering to DevOps to backend engineering to product management. I've worked with systems serving tens of users and tens of millions of users. Happy to answer any questions. I love this shit.
If someone could figure out a trustless, decentralized way to implement a CDN, I'd eat that up in a second, but with my current understanding of the internet and available technologies, I don't see a way it can work. At least, not with making every web page take >3s to load, which would absolutely kill websites.