Not only is this a metric that doesn’t make any sense, simply floating the concept that this metric corresponds to anything in real life is harmful. Teams are

Not only is this a metric that doesn’t make any sense, simply floating the concept that this metric corresponds to anything in real life is harmful. Teams are social constructs, and you simply cannot apply an algo to some observable code metric and get any kind of proper result. People leave, others step up, or don’t. End of story. The problem with these kinds of metrics is that even if people know they are ridiculously off what they mean, some still think that the idea they convey is correct: ie. That if x people were to leave, the project would stall. That premise is simply not true. Don’t even think about this stuff. It’s stupid. If you want to know more about these risks, talk to the team. People on the team know if anyone is irreplaceable.