> Everyone knows this is best avoided if possible. The vast majority of OO languages provide mechanisms to avoid mutability e.g. data classes or keywords to make references constant.

Well, clearly not everyone knows it.

My biggest complaint about languages that incorporate functional features is that immutability is most useful when it’s the 99% use case.

When it’s a special tag that may or may not be used within the library/code base you’re using, you don’t get the cognitive advantage of feeling confident you can judge the output of a function by reasoning about its input.

My brain is small. I need all the crutches I can get, and referential transparency is a huge advantage.