Let's Encrypt is a non-profit that defeated the certificate cartel. The main thing you get from using HTTP without it is bad security.

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.

No root certificate is decentralized.

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.