> Use HTTP (secure is not the way to decentralize).

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.