> At a large enough company you continuously lose people for natural reasons, like retirement, moving for a spouse, moving to be closer to family. Past a tipping point you're just always hiring.
As an analogy it's kinda like hard drives: when one of my hard drives dies, it's An Event which I need to deal with specifically; I need to order a replacement for that specific drive. At Google's server farms, hard drives dying is just a statistic, you continuously buy hard drives just because you know existing drives are gonna die at some semi-predictable rate.
It's not really an analogy, it's just facts of life. In a large enough company or over a long enough time period at a job or in your career, realistically people actually will eventually die and cause vacancies. I've had two coworkers die, one because of illness, the other because of an auto accident. I stopped using the "bus factor of one" phrase as a result even and use "redundancy or succession planning" since it's not outside the realm of possibility that someone might get hit by a vehicle.
As an analogy it's kinda like hard drives: when one of my hard drives dies, it's An Event which I need to deal with specifically; I need to order a replacement for that specific drive. At Google's server farms, hard drives dying is just a statistic, you continuously buy hard drives just because you know existing drives are gonna die at some semi-predictable rate.