Say that made 3 revenue products revisions slip by 2 quarters, and not ship six cost-saving optimizations (if you make google search 0.001% faster, you save millions in compute). Further, say that made 100 companies not renew their 7-figure ad contracts. If all of this was evenly spread throughout the year, it still hits revenue and profit only a comparitive small amount in one year.
It takes time for those sorts of changes to propagate all the way through the system until they finally impact revenue and costs. The effects are long term.
I'm on record as saying that Google hired way too much and way too fast, but it isn't quite as simple as, X-people produce Y-revenue, so (X-1)people produce Y-Z revenue.
I mean that in several ways: Google doesn't have nearly as good a record of successfully recruiting (or retaining) top-tier talent as they did just 5-10 years ago. It is no longer seen as a dream position, or even a strong candidate's first choice. Similarly, hiring managers who see Google on a resume don't treat it as highly as they did 5-10 years ago.
Google is rapidly on its way to becoming just another big boring technology company, like SAP or Salesforce or Oracle. Now the culture of those around it has finally started to catch up.
Of course, the counter argument is that technology allows Google to do more with less people. I am not convinced by this argument, because Google's competition has about the same ability to do more with less people. If you can improve individual productivity than why not scale that across more people.
To summarize, this indicates to me that Google is reducing their value on human capital.