I was going to write a question asking if reduce is the thing I know as accumulate (I think I picked this up from SICP). But then I went to wikipedia, and it seems that an even more common name is fold.

Here's a hypothesis: The fact that the same operation has half a dozen different names makes it sound like there is a lot to learn. If I am totally familiar with fold, and i come upon a reduce, I may need to think more about what's going on, which is distracting.

I don't think map and filter have so many synonyms? I know select for filter, but it seems to me less common.

And in some contexts you have the subtle distinction that fold is linear and reduce requires an associative operation and an identity element (aka a monoid)