Exactly. Bare tanks can be a formula for requiring more water changes (or bigger filtration) than an ecologically more active/balanced tank. It's why, for example, some discus keepers think you need big, daily water changes. Big protein, heavy feed, bare tank, a fish not fond of a lot of current and, sure, you would need lots of water changes. However, not necessary with a different approach to keeping them that includes a more ecologically balanced tank, more moderate feed/protein, etc. I know, I kept them for years and, yes, they still got big... Just an example, same principle for any other fish I've kept and bred, new or old world.One of the problems I see in not using substrate, is lack of surface area for beneficial bacteria.
With sand or gravel, every particles exposed area, crack or crevice has surface area for benefials to colonies with biofilm. With bare bottom you reduce that area significantly.
You can make up for it, by having over filtration, with lots of extra media.