This is insane, how does it make sense? Employee salary expenses are no different from other expenses to run your business. Imagine they did this for raw material instead, a restaurant could only expense 20% of the food that they sell. If they purchased $100 worth of food, but could only sell $50 worth of it, they have to pay tax on that even when making a net loss overall. It just does not make any sense. There would've been a huge uproar if this was done for cost of goods. Why are employee salary expenses any different?
There are other expenses that are also amortized.