In their defense, this looks like content marketing for people who buy functional programming consultancy services. So they're not really writing for a general audience. I tend to agree on initializations though. I think a lot of times people use them as a signal of their membership of the technical "in group", to establish a place in a social hierarchy. That's not good communication.
A simple rule: if you're writing for a more general audience, always spell out your initializations the first time you say them.