It would allow the developer to choose the appropriate amount of parking spaces for their building, instead of being forced to follow the requirements resulting from central planning by the city administrators.
They cannot simply rely on on-street parking instead, since (per the second bullet point) the prices would for those parking spaces would increase dramatically, providing the developer with a competitive disadvantage.
I could see this working out perfectly fine for businesses who compete for customers, as those will likely be very sensitive to the cost of a parking space. However, for buildings where people do not have a choice of whether to travel there, this seems more problematic. Imagine e.g. a courthouse – missing parking spaces would just impose a negative externality on the unfortunate “customers”. I guess the question is in which category office buildings and residential areas fall into, arguments could be made either way.