[Obi_Juan_Kenobi]

You misunderstand.

We've being doing genetics for decades. Molecular biology without mutant studies wouldn't exist. It's the foundation of the field.

All this is is a difference in scale. But it is a very crude tool; really understanding gene function involves studying it in relevant contexts. Looking at cells in tissue culture can give you some ideas or hints about how it functions, but the critical insight might require certain cell types or gene regulatory environments.

What data like these do is inform hypothesis generation and refine the interpretation of genomic data. It is important work, but does not replace doing actual biology.

What you're talking about is essentially saying we just invented molecular biology. Which is obviously not the case.