> Mutation is just inherently more complicated than storing immutable events.

Not really. This blog post is mutable. There is nothing more complicated to it than to an immutable event. 

> If they can just edit it out of history, that is lost.

It's not an edit. It's a new signature. You are free to keep all versions if you want to audit people. Also, almost all relays delete regular events. So, I would argue that auditing is exactly the same between replaceable a non-replaceable events. As we move along, relays won't be able to keep more than a few weeks of data for all their users. So, every event will disappear in time. 

> For that reason, my FeoBlog system disallowed mutability.

You are free to force yourself to do this. But you are not free to force that decision on everybody else. If people want replacements, they will have replacements. 

 Have you ever listened to Rich Hickey? He makes a strong case for the complexity involved in conflating names with data.

https://www.infoq.com/presentations/Value-Values/