I'm saying it's not even an extreme, in that I don't believe what people are calling "immutable infrastructure" includes that.

If your biggest objection to an idea is that you can make up a silly thing that sounds like it might be related, I'm not understanding why we need to have this discussion. I'd like to focus on real issues, thanks.

I'm not objecting categorically to anything. I think that immutable infrastructure is a spectrum, and depending on your needs you may have just about everything immutably configured, or almost nothing. I just don't think it's so black and white as "you should always use immutable infrastructure."

I also think it's a cool idea to destroy the entire cluster just to add a node, and it sounds ridiculous but also like there's some circumstances where it makes perfect sense.

Again, do you have a citation for the notion that it's a spectrum? The original post that coined the term doesn't talk about it that way, and neither do the other resources I found in a quick search. As I see it, it's binary: when you need to change something on a server, you either tinker with the existing server or you replace the server with a fresh-built one that conforms to the new desire.