One of the main goals of not using CO2 is reduced growth and work/care.
Doing water changes is not required if you add plenty of plants and reasonable stocking levels of fish. Maybe if you hack some plants out and make a mess once every 6-12 months, but part of the issues with non CO2 is adding new freshwater from the tap adds CO2, this gives a spike of CO2 that algae respond to much faster than the plants do. If you leave things alone and have some patience, allow a reasonable stocking list of fish with algae eaters, then you can avoid all water changes for months, years even.
Been doing it for decades.
With CO2 enriched systems, you can use water changes to balance the nutrients which are used up much faster and need some supplementation as well as not worry about CO2 since you add it anyway......whereas the non CO2 method relies on the fish waste = plant demand, perhaps the sediment and some minor supplementation and then very small amounts at that, and no water changes.
They seem contradictory, but if you consider the rates of growth of plants in each case(one very slow, one very fast), the balance and practical matters, plants will adapt well, as long as things remain stable.
Plants grow both for the same reasons, just at very different rates. Non CO2 is limited by light and CO2.
Regards,
Tom Barr
