Because there are no valid objective qualities as to why functional programming is any "better" or "worse" than the alternatives. At the end of the day, you're

Because there are no valid objective qualities as to why functional programming is any "better" or "worse" than the alternatives. At the end of the day, you're instructing the machine to do the same work, regardless as to the structure of the code you're writing. Functional vs. an alternative is nothing more than visually different styles that result in developers having a personal preference. Some languages offer optimizations for certain constructs, but even those depend on the implementation found in each language. A functional language doesn't automatically grant objectively better qualities, whereas a specific functional language might provide advantages that have everything to do with that specific language rather than the fact it happens to be functional. Functional languages are interesting and the right tool for the job for many people. But they are not better, and when you have developers fighting hard to defend their language as "better", recognize that has a lot more to do with their ego than anything based on facts.