Hello; Another way to consider it is that along the many hundreds of miles that the water flows thru the various tributaries of the Amazon they are picking up all sorts of material and are teeming with life forms. The life processes of the creatures are also affecting the content of the water. At any one point along the way the water will be loaded with things that can be called water parameters. It seems to me that what matters is the quality of the water at any time more than how much may flow by. It may well be that many aquariums have as good or better water parameters than are found in nature.
An analogy may be that if you wash clothes twice and they are clean, then washing the clothes three more times may get them marginally cleaner but the percentage of improvement is likely to be tiny. My take is that if the water parameters are good at one level of water change % and frequency, then larger amounts of water and more frequent changes add little to the quality of the water. It then may become an exercise that makes a fish keeper feel better about his/her industry but likely adds little to the environment for the fish.
I tend to go with the idea that if the water parameters are good at a particular water change regimen, then additional quantity and frequency adds little. In the end we each get to run out tanks any way we want.
Good luck
