Yes, search and ads are the golden goose but so many things contribute to that success. Chrome, for example, is absolutely crucial to search quality. Maps is huge. Android is also critical. Search and ads use a whole bunch of infra (eg Borg, storage, load balancing, serving infra, traffic management, data center infra and so on). Even the people who manage all the corp Linux distributions and video conferencing infra contribute. Source control, build infra, testing infra and so on.
Deciding who does and doesn't "contribute" for something so interconnected like this quickly devolves into a political exercise at best and a popularity contest at worst.
