Namecoin is the best example of a real world use case, a proper replacement of a DNS with no central authority. This is clearly one which is very difficult to replicate reliably without a blockchain.
Moreover, at the end of the day, even DNS is a matter of "real world truth" and there's no reason a vote by miners would be particularly reliable source of this truth.
Right now, accurate propagation of settings throughout DNS kind of assumes a lot. I don’t think Namecoin captures incentives properly either, but I can imagine some blochchain system connecting the dots.
You can't switch from the ICANN, no matter which domain you chose, it depends on them, they effectively have a monopoly. I want to self host my domain name.
> What if someone spams the ledger with too many names
You need to pay in coins to register a namecoin domain so this attack won't work.
> What if someone takes domains that should be illegal for them to possess?
This should be up to courts to decide if the name is illegal and handle it over, not to some random organisation like the ICANN which has no legal basis.
> What if someone takes someone else's private key?
Same as if some gets access to your registrar password right now, nothing changes with that.
> What if an organization gets their private key stolen?
Again, same as before, nothing is improved or changed by a blockchain here.
That's not an argument against building something...
> which they're far from - why is a 'central authority' inherently bad?
They're not. Sometimes you want a central authority, and sometimes you don't. Both modes can be good. But previously central authorities were necessary due to the physics of DNS. Blockchain enables a new mode. Now the two modes can compete, and we can reach a new equilibrium with both, or one can win out. That's what's cool about it.
At which point did I argue building things is bad? I actually took a lot of time to learn Ethereum smart contract development just to get to the bottom of the whole blockchain ecosystem. Learning and building are almost never bad things.
I'm not bashing the idea of competition between blockchain and traditional centralized authorities either. I'm extremely pro-competition. I'm bashing the fact that all - yes, all - blockchain applications provide negative value compared to their traditional counterparts. The argument that blockchain enthusiasts use to justify their support for such low-quality infrastructure is this philosophy that having no centralized authority is, by itself, valuable. This is what I'm bashing.