That's one more misconception I saw, to keep the fish in smaller tank. Some believe larger tanks stress them out. May be they do if fish was kept in a very small space most of the life and then moved to bigger one. Another reason I see is they want more flowerhorns in limited space and owners go for quantity of fish they can have vs quality of life of the fish.Not really my style of fishkeeping or preferences... to each their own I guess. I won't put someone down for liking or keeping Flowerhorns. Real flowerhorns are obviously flowerhorns, where it becomes a problem to me is people breeding hybrids that don't look like flowerhorns (think jaguarxconvict, etc) and them getting out, muddying the bloodlines up. Even if the first breeder is responsible and says what the fish really is, the next owner down the line might not be, and so on, until it's hard to get a pure bred fish.
The other problem I see with the flowerhorn community is that I see many owners think flowerhorns are fine in a very small bare tank. I think the fish should be kept in an adequate sized tank so they can swim around freely and not just bang into the glass all day. And they would probably appreciate some décor. I know it would have to be softer décor so the fish don't hurt themselves on it in a fit of rage... but silk plants and the like would be better to me than a bare glass box. Just my .02, there is debate about this and I'm sure some would disagree with me and say they prefer the bare tank. Doesn't make sense to me though.
About decor, agree it's a debatable topic, I have artifical driftwood in my tank, that's not sharp, looks good, doesn't alter water params.