Ultimately, I think we have a simple hobby. I've had aquariums for 60 years. What's changed in the freshwater hobby?
We do water changes. The balanced aquarium myth comes back, like all myths that say what we want to hear. But it doesn't work, and we can only get close. We know more about the biological processes aiding the chemical processes of the nitrogen cycle. We know more about fish evolution and how minerals in water operate with our fish. We know more and have better tech, but it's to do the same things.
Manage water quality. Keep fish alive and well. Feed fish and plants. Make it look good.
We've added shrimp.
If I set up a tank with the stocking I like, I need a filtration system, a glass box, sand, rocks, plants, root tabs, a light, maybe a heater. My killie tanks needs air driven filters and a cover, just as they would have in 1940. If I stock super lightly, I don't need a filter, though I dislike those tank set ups and won't do that. They're so narrow in what fish can live in them.
But we ask the same questions.
And after that? I've seen some 1930s aquarium gear, and it all attempted to solve the same problems we have now.