Perfect isn't real

Service levels, the expected probability a company accepts of avoiding a stock out,  DO NOT produce the probability of not losing sales.  A service level greater than 95% is an indicator that something is horribly wrong.

 The closer you get to a 100% service level, the faster your inventories and carrying costs (operational expense) are going to rise.  A service level of 100% is only possible with an infinite supply of safety stock.  An infinite supply of safety stock means inventory and operational expense are increasing, and throughput is decreasing.

 Demand and lead times are stochastic.  The best forecasts will never be 100% accurate.  Perfection does not exist. The pursuit of perfection will cause a company to move away from profitable operations.

Inventory strategy mitigates the risk of a stock out. 

Inventory strategy keeps inventory levels at manageable levels; which reduces operational expense. 

Inventory strategy makes a company more profitable.