An old-school consensus from 40 years ago it was stated in every aqaurium guide that waterchanges were an absolute nono. We only topped what was evaporated, and this was very little because most tanks had hoods and glass cover panels to fit the tube lights. Tanks should smell like old sludgy sinkholes and old aquarium water received holy properties. Then we kept it running till the Old Tank Syndrom kicked in and started over again. And nobody knew when that would be. But it would always be years. And in my personal case back then, I can't say I experienced it negatively. It was simply how it should be done.
Back then it was mainly Eheim, Sera, and Dupla as leading brands sponsoring the publishing of aquarium guides. It all was definitively based upon professional opinions.
I remember a story from the 1980s where a German fish breeder suffered from a seemingly uncurable fish disease. And for the professionals with large installations they thought that next to no need for water changes that filters also shouldn't be cleaned. Anyway, after a long period of searching for the cause of the disease. They finally found out that the filters were infected with all kinds of nasties, making all the fish and their fry sick. And after draining and cleaning out the complete installation and start fresh again, the problem was solved. I believe this incident was the trigger for professionals to change from the water change Nono, to it could be rather important. And their consensus changed around this era.
Much later Diana Walstad picked the idea back up and scientifically underscored this old-school practice and states in her book "Ecology of the planted aquariums" that if sufficiently planted, there actually is no need for water changes. The ecology in the aquarium will deal with it on its own devices. In a later 2nd edition, she revised this idea and advocates that water changes only are of some importance to minimize the risk of accumulating pathogens (such as fish TBC) and went from no water changes to periodically only 10% because pathogens accumulate only in the oily biofilm at the surface.
I guess in modern times and the popularity of open-top tanks scaped and viewed as an art form also increased the idea of sufficient water changes as good husbandry. Mainly derived from eliminating the possible unpleasant smells and keep the water as clear as possible to a certain degree. And obviously, the glass panels are easier to clean when the tank is partially drained. This makes water changes more of a practical (husbandry) than ecological importance.
I still today know somebody personally with a lush open-top planted aquarium in the bedroom 20 meters away from the first tap in the house. And it's simply laziness but she never does water changes and only tops off what evaporates. If she does it might be once a year only, I guess because then it starts to smell... She has aquariums for about 12 years now and never changed the water and never suffered any problems. Lately, her 12 years old Labeo bicolor died of old age. It survived all these years and stayed strong and healthy.
Not my kind of husbandry but I guess the proof is in the pudding. Diana Walstad is correct after all...
From an ecological standpoint of view, it seems the importance of water changes resides in your peace of mind and being hygienic.