It seems like you're saying that abstractions are worthless unless they're perfect, which is obviously not true.

> Since we are not quite there yet, could you explain in broad terms how a large collection is sorted while maintaining performance and immutability.

What do you mean by "maintaining performance"? Relative to what? Who's asking for the sorted collection? How are they going to access it? What are the resource constraints? Give me a real-world example.

Don't get me wrong, I'm not saying that FP is the answer to everything. It's a useful tool, and part of being good at software development is knowing what tools to use and when.