But the balance sheets encompass more than delivering value to end-users; business can and do trade off that value for some money elsewhere (see e.g. pretty much everything that has anything to do with ads).

Note also the potential deadlock here. Optimizing core calculations at μs level is bad because UI is slow, but optimizing UI to have μs responsiveness is bad, because core calculations are slow. Or the database is slow. This way, every part of the program can use every other part of the program as a justification to not do the necessary work. Reverse tragedy of the commons perhaps?