Oh! My mistake. I guess I'm a little unclear what the problem is with that. Generally parameters for lab values, vitals, and so on are based on rather large data sets, and the official normal range is set based on what trend your're seeing.
So a person with a heart rate below 60 tends to start experiencing problems, and a person with a heart rate above 100 tends to also start having problems. So, 60-100 bpm is a normal heart rate. Are there people who do fine outside those parameters? Absolutely! Medicine is not a one size fits all proposition.
Still, it's good to have a starting point, so you can be alerted to look for certain things in a patient if a vital sign (like blood pressure) is outside the norm.