water changes not affective at controlling nitrates?

While somewhat misleading, I believe the author is trying to convey (in a somewhat overly dramatic way) the (I believe false) old adage and idea that a monthly water change is sufficient for healthy fish.
I change about 20%-30% per day in summer, have planted refugiums, and use pothos, and my nitrates hover at about the 2-5ppm range.
Most natural unpolluted waters have a nitrate level of <1ppm.
To me the difference between over 20ppm nitrates and the pristine 1ppm, is like the difference of humans that live in smog, or smog free air, as far as health issues are concerned.
If you keep fish that normally come from eutrophic waters such as many anabantids do (but also take in atmospheric air), a monthly water change may be sufficient.
If you keep rheophillic cichlids , or other sensitive species like stingrays or dorado, a water change every other day may not be.
To me, the plethora of HITH and other posts in the MFK disease section is an indication of the importance of keeping to a more rigorous approach to fishkeeping than the accepted norm.

I don't think the numbers in the article are flawed at all, (most people, like the 2nd poster, believe it is a bit dramatic) the author says in the paragraph preceding his calculations, changing 50% per week, (and many aquarists think that is a huge water change (and most, at best change 20%-30% per week)) will "not" be sufficient,
and I agree, if you want what I consider a safe nitrate level.
But the toxicity of nitrate is to some, debatable.
To me, it is not, and I, in my 20%-30% per day daily water change routine, change over 120% per week.
And use pothos, and planted refugiums.
Still my nitrate concentration hovers at 2-5ppm.

Its really not that hard, I open a valve, and instead of going to the sumps, old water from the tanks flows outside to my garden. Takes 5 or 10 minutes to loose 300 gallons of day old water from the tanks, and water the garden at the same time. Open another valve, and new water goes from tap to my sumps/tanks.