Assuming they rebuilt an exact replica of your software, there is a misaligned incentive at play. The hiring manager don't pay the 19 new hire salary out of his

Assuming they rebuilt an exact replica of your software, there is a misaligned incentive at play. The hiring manager don't pay the 19 new hire salary out of his own pocket, the hiring manager don't build the product directly. No one get fired by hiring bunch more people. On the other hand, arguing a, for example, 50% effort does have a negative impact to whoever making the arguing. Even more so if it means fighting HR bureaucracy. Imagine the salary is benchmarked against some sort of "industry average" and you have to convince people that you are maybe 100% better than average. So assuming you are still playing the employment game, maybe next time you can make arguing for you easier.