The issue is not that obscurity per se is bad, but relying _only_ on obscurity is absolute the same as not having any security measures at all.
With the public ledger or not, you will still need to implement proper security measures. So it shouldn't matter if your address is public or not, in fact making it public raises the awareness for the problem. That's the argument.
> So it shouldn't matter if your address is public or not, in fact making it public raises the awareness for the problem. That's the argument.
Forget about the internet, we've had almost 100 years to prove we can secure identity theft. And the best thing we can do is to keep our SSN's secret -- security through obscurity. Keeping your SSN private reduces your personal attack surface.
We've had 50 years to secure the internet, and yet, we still have zero day attacks. Nuclear submarines try their best to keep their locations a secret? Why? You cannot attack something you cannot see or hear.
> relying _only_ on obscurity
Until it gets obscure enough that we start calling it “public-key cryptography”. Guess the prime number I'm thinking of between 0 and 2↑4096 and win a fabulous prize!