... But people and genetic testing companies seem to want to keep it going.
[1] - https://embryo.asu.edu/pages/george-w-beadles-one-gene-one-e...
You can still get alot of mileage out of a simplified, inaccurate model. If you just say to yourself, "well, this whole gene thing is hopelessly complex", then you'll never get anywhere outside of a lab or personal project. Applied biology especially, and medicine in particular, seems to require grossly simplifying assumptions in order to make any problem tractable.
I would think that would be understood by people on HN. One of the biggest impediments to smart people starting companies is an inability to set aside the inherent, irreducible complexity that they, alone, see and appreciate. The people who succeed in business tend to be those ignorant of the complexity[1], or those able to come to terms with the reality that any practical, marketable solution is necessarily built on an inaccurate model of the world and is doomed to eventually crumble for its inherent flaws.
The old adage that ignorance is bliss is more insightful and meaningful than people give it credit for. Knowledge, especially epistemic knowledge, can be debilitating.
[1] Which doesn't imply being stupid or incurious. Willful ignorance seems like a potentially useful strategy.
BRCA and heart disease come to mind.