I am mindful of a quote of Clement Freud's: "If you resolve to give up smoking, drinking and loving, you don't actually live longer; it just seems longer".
OK, you can keep bettas in tiny one gallon (or two gallons or whatever) tanks all by themselves, but are they having fun? Do they have much of a life?
What do they do in the wild? They certainly don't live in puddles all by themselves. Surely, the best tank for a betta would be one that had a very weak water current (if any at all), masses of live plants, and peaceful tankmates suitable for a Southeast Asian still-water habitat, such as dwarf rasboras, gobies, and so on.
What I wonder is whether the arguments about what artifical strains of Betta splendens "want" is similar to that farmers make about keeping chickens in battery cages: they don't get sick, they don't fight, they grow faster, it's easier to check their health. All true, but what kind of life is that?
I'm not saying mix them in with fish that will attack them, or keep them in tanks with power filters and water currents that wear them out. But isn't it more ethical to give a betta a stimulating life where it gets to explore, hunt for food, express its territorial behaviours, and generally have whatever is considered "the good life" in the betta world?
Cheers,
Neale