It is a very simple reason: abstraction. The more abstract a software is, the less efficient. But it is also more flexible, easier to understand and modularise

It is a very simple reason: abstraction. The more abstract a software is, the less efficient. But it is also more flexible, easier to understand and modularise, and specially way cheaper and faster to develop. Of all of the above cheaper and faster to develop is the main reason, by far. It is also safer with fewer bugs. Software engineers are very expensive, the harder it is to develop something the longer it takes, the higher the economic risk. To make something the "old way" takes years of work. People are not willing to wait nor pay for that, and the low level technologies will change over time so you could get trapped in a never ending rat's race.