[author] Unfortunately yes. It was not the only thing happening at the time. FB had just gone IPO and this put a huge amount of pressure to grow revenue. When I joined the Ads org in 2012, it was about 100 people I think, with just a few products. When I left in 2017 it was well over 1000, and my job had changed to managing relationships with 55 other teams, all of whom depended on my teams product to ship their individual features (think Video ads, Carousel ads, hundreds of others).
So, while doing the rewrite, we had to transition from being a product org, where a few engineers built all features for a bunch of back end teams, to an infra+product team, where we built all sorts of support for all the new teams that seemed to spring up weekly.
If we had done only the technical rewrite, and not enabled all these other teams to ship their products on the UI surface that our customers actually used, FB's revenue would not have gone from $4B when I started to around $30B when I left.
