>just to do the math for you, a 1 year average tenure would be
The guy I replied to did say median tenure (where I was talking about mean or average tenure), so relative to a median tenure sure, doubling the staff would do that.
But you said average, in which case no that isn't true. Google is a 26 year old company. If you randomly distributed tenures across a hypothetical employee base (1-26 years), it would take something like 1200% growth to get the average tenure under 2 years. And of course Google's actual employee count growth rate over the past decade and a half is more in the range of 12%, so a couple of factors off for that.
Even when people say the average tenure is 3 -- doubtful -- that still requires an insane level of turnover for a company growing so slowly, relatively, and being so old.
> Almost all tech companies target firing/pushing out a considerable percentage of employees per year.
Not firing, but managing out. It's very different culturally.