And pubic and anal hair is meant to waft the pheromones from those regions too? :)

Unironically yes: https://en.wikipedia.org/wiki/Skatole

However, it strikes me as more likely that pheromones are emitted in places already adapted for evaporative cooling, which in turn would be hairy places, which in turn could be lubricative.

OK but why are the pheromones in your armpit instead of your elbow?

You might be reversing cause and effect.

Evolution, though directed by natural selection, is a random process. So sometimes the answer's just because that's how it happened.

That's not an answer to why selection made the decisions it did.

Just because it's not satisfying doesn't mean it's not an answer. Evolution is driven by random mutations in DNA. Sometimes they're beneficial, sometimes they're harmful. In those cases, natural selection determines whether the individuals with a given mutation will survive and pass on their genes. But sometimes, mutations are neither beneficial nor harmful, and which one beats out the other (if either does) is simply random chance. So many times, questions like yours are unanswerable.

Local maxima that can not be left anymore with the given mutation rate.

Better alternatives for so many functions that were never explored/reached by evolution.