Questions arise regularly about alternative blockchain DNS projects such as
Unstoppable domains or
Handshake domains in comparison to Namecoin. First of all, generally all of these blockchain DNS projects are auction-based systems. Once you have an idea of your preferred domain, you have to share it publicly and compete with everyone from all around the world, and the prices for attractive domains are pushed like on eBay auctions.
Secondly, for instance Unstoppable domains are then registered for an indefinite period of time, Ethereum domains may be for lifetime (depending on the payment). While this is attractive to a domain owner, the domain expiration of Namecoin domains after 36,000 blocks has a purpose at all. Without domain expiration, domains would be reserved indefinitely, even if they were no longer in use. No one else could ever use them again. That would make the entire blockchain DNS more or less useless within a decade.
Last but not least, accessing these alternative blockchain domains becomes a nightmare when browsing with a popular mobile browser or accessing SSL/TLS-protected websites in HTTPS mode.