Google absolutely does not make company-wide technical decisions and then the entire engineering crowd goes there. Rather, they make company-wide technical decisions, and over a period of 3-5 years the entire engineering crowd gradually gets there. As we used to say: "There are two ways to do everything at Google: the deprecated one and the one that doesn't work yet." In some cases I've seen up to 3 deprecated systems in flight, plus one that doesn't work yet. Borg's predecessor was finally removed from production shortly before I left in 2014, despite being deprecated around 2005.