Why shouldn't we talk about net profit? Taking 30% off the top can quite easily mean the difference between viability and not, quite easily, when you factor in

Why shouldn't we talk about net profit? Taking 30% off the top can quite easily mean the difference between viability and not, quite easily, when you factor in employees, rent, marketing, legal fees, and absolutely everything else. Isn't this precisely what the discussion should be about, whether it makes non-viable a lot of businesses that provide value to people?