You see, that's fine for some situations, but it's still not as generic than what I'm proposing, as it fails for mixed modules setups. In the example you show in the images, say I want, for instance, instead put one more productivity module and one speed module after the upgrade. Not doable with ...

Very minor, but still slightly annoying. Sometimes, you upgrade an assembler and put different/more modules in it. You then want to copy that and paste it into an entire assembly line. Problem is, you cannot do that without forceful pasting (control + shift), which is bad because if you do so, you ...

The article in question is https://wiki.factorio.com/Tutorial:Quality_upcycling_math

The text above the table says The columns "X products" denote modules need to install into the machines that are set to produce items of X quality.
However, looking at the table it recommends using quality modules ...