Earlier quoted context omitted.
By your logic, IKEA is the highest quality furniture because it's in more homes than for example Herman Miller furniture.
But that’s not my argument at all. I’m saying that quality is impossible to measure if 0 people use it. Once you go above 0, it can be measured and it’s not necessarily related to how many people use it.
It is still possible to measure the quality of software (or other products) simply by defining a metric that proves quality and testing for it
If I were to write 2 simple functions that reverse an array, and one successfully reverses an array and the other just randomizes it - despite never using this function, we could all agree that function 1 is of higher quality than function 2.
This is an extreme example but the same can be done for, lets say, speed or error handling.