I think most of us know that
address reuse is a bad idea and it's better to use a unique one for every transactions to avoid security and privacy issues. If a website owner accepts bitcoin deposits and a user wants to withdraw coins to an address which was already used in the past, should there be a warning or even an error message or would that be too annoying for the user?
I'm curious about your opinions!
Reuse of an address is the sole business of its owner. It's a matter of choice, for most people simplicity is the most important.
So imho, while talking about a coin that's about freedom.. asking about banning / blocking the freedom of choice is absurd.
Hence my answer is clearly NO! No blocking!
A warning can be done, because it helps the users learn and get more aware of what their choices mean. But that's all.