Because this defense doesn't solve the issue that the water is being used faster than it's being replenished. The biggest issue with this is on wells which are sucking so much water out of the ground it's collapsing the ground itself, in ways that are likely permanently lowering the water capacity of the ground. Even if it doesn't the run-off water isn't going back into those deep aquafers.
Eventually making it back into aquifers could mean that in 500 years it mostly ends up in an aquifer near somewhere 500 miles down river/wind or something similarly unhelpful to the region in the short term.
Perhaps it's the same reason that in the Yudkowsky vs Hotz podcast yesterday, Hotz didn't know what a gelding was despite being incredibly smart -- zero farm experience.
To be fair, geldings aren't really a part of modern farm life. Steers and barrows are still common if you're in livestock, maybe wethers, but horses are more a hobby and only coincidentally associated with farms.
I mean, farms come in a lot of varieties. Entirely possible for one to be successful at cranberry farming but know little about many/most/all animals (that don’t attack their crops).
https://blogs.agu.org/geospace/2019/03/19/western-droughts-c...