This doesn't seem like useful advice. If you're going to use HTTP at all there is essentially zero practical advantage in not using Let's Encrypt.
The better alternative would be to use new protocols that support alternative methods of key distribution (e.g. QR codes, trust on first use) instead of none.
> Selfhost DNS server (hard to scale in practice).
This is actually very easy to do.
DNS is easy for yourself, but if you host it for others (1000+ of people) and it needs to have all domains in the world, then it becomes a struggle.
DNS can answer thousands of queries per second on a Raspberry Pi and crazy numbers on a single piece of old server hardware that costs less than $500.
If your DNS port is closed by your ISP, you can't have people use your DNS server from the outside and then you need Google or Amazon which are not decentralized.
Also to be selfhosted you can't just forward what root DNS servers say, you need to store all domains and their IPs in a huge database.
Also if people need more food for (decentralized) thought: