That is true alot of my africans are kept in whatever comes out of the tank and some surviving ones that were supposed to be discus food actually grew very fast in my discus tank..
They wouldn't do well in very soft acidic water and the addition of anything to make it harder or more alkaline would make them happier.
I had a tank full of africans when I first started and chucked a piece of drift wood in there, the fish were all fine happy and swimming around until 2 days after the drift wood after that they just sulked and sat around under the rocks hardly eating etc took me a week to figure out the ph was around 6 and the driftwood had dropped it, I removed the driftwood and chucked some coral in and the fish picked up again... Maybe they would have got used to it and cheered up but they weren't happy. I have heard that fish absorb the calcium and that out of the harder water to grow and develop, if a fish comes from an area where in the wild there is lots of calcium it wont do so well without it in its tank, and vice versa with softwater fish.. Unsure if this is true but it sounded interesting to me.
With fronts I would say its more having a tank that is big enough for them.