By "pivot into mobile" I suspect the other poster is referring to Facebook Home, an ill-fated Android skin and line of smartphones.

https://en.wikipedia.org/wiki/Facebook_Home

No. Back when smartphones were still in the process of taking over the market, Zuck saw the adoption curve and realized that future ad revenue would be from phone scrollers.

At the time most features were designed and implemented first for desktop and later ported to mobile. He issued an edict to all hands: design and build for mobile first. Not at some point in the future but for everything, starting immediately.

Maybe this doesn't sound major, but for the company it was a turn on a dime, and the pivot was both well informed and highly successful in practice.

Call me classic and old school. But I call a company succuessfull if it actually does make more money than it spends. Everything else is just driving dept and economy but no actual success