1. Judging how smart the people there are by their tech stack is like judging how much horsepower a car has based on how many miles it has.
2. Even humoring that assumption, you’re conveniently forgetting React, Hive (+Hbase, hipal), presto, rocksdb, Cassandra, graphql, oauth 2, open compute, phabricator, hhvm, buck, and that’s just the open source stuff.