I was there and it was not being used in new projects. Maybe that spam filtering service has existed for that long. I would definitely not say that pinterest has fully bought into using elixir because of cost savings which is what the article seems to be insinuating.
There was a point like 8 (ish?) years ago where Pinterest wanted to consolidate on a single backend language internally, after it became apparent Python was not suitable, and multiple contenders were being tried in different places. I think at that time Steve was advocating for Elixir to be it. However it ended up being Java.
Nowadays, kind of ironically after the consolidation, we have backend services in at least six languages I can think of. Which is just the reality of how things play out for a tech company doing acquisitions. But yeah we’re not making new ones in Elixir.
