Earlier quoted context omitted.
In the first year, you only get to deduct 20%. But in your second year, you get to deduct 40% (20% from the first year and 20% from the second year). In the 3rd and 4th year it's 60% and 80%. And so on until you get to steady state of 100%. So, no, it is not "really bad" for you. You as the owner might not make as much money for the first year, but you will be at steady state in a few years, and you get to deduct the…
I think an implicit assumption here is that the company is able to survive the five years. This rule affects cash flow in the initial years pretty hard and a lot of small companies cannot survive that.
This really only affects software companies that are profitable in their first year, which is a very small minority.