also when you need to develop a new feature and it needs to go through A:B testing frameworks, localization (including Arabic Right to Left text/layouts), phased feature roll outs, 99.999% reliability, integration testing, planning for use cases anywhere from LTE/WI-FI in USA to EDGE network in developing countries, and you need to build the tools that do those things too. Clearly the 100 engineers are sitting there twiddling their thumbs.