I think there is far too much emphasis placed on high current flow rates by many aquarists, for many species of fish. In the Canadian waters where the bulk of my observations take place, species that are commonly thought of as preferring or requiring high flow rates still spend a great deal of time simply resting in the low-current or "slack" water behind boulders, logjams, etc. and only dart out into the current to snag a prey item or other food morsel that comes by. This type of behaviour is well-known to fishermen pursuing trout and other species who live in this type of water. These fish certainly require high oxygen levels, but they don't spend all or even much of their time wasting energy fighting the high current. Occasionally, perhaps immediately following a hatch of some aquatic insect species, the fish may exhibit a feeding frenzy...a "bite"...that is very reminiscent of the behaviour of aquarium fish when the owner approaches with a can of food in hand. During these feeding sessions they may remain in the main current for many minutes, gorging on a temporary bonanza of food...but those periods of frenetic activity, both in the aquarium and also in the wild, are relatively brief.
I read a post recently here on MFK in which the poster expressed some level of surprise at the reaction of his fish to an increase in flow rate. A new/bigger/faster/more-powerful pump had been installed and dialed right up Heavy Rinse levels, and the fish did what most of them do in nature in such conditions; they huddled in the lee of rocks and decor, conserving energy. Imagine that! They didn't want to fight the current continuously...just as cheetahs don't spend all their time running at 60mph and whales don't dive to hundreds of feet while holding their breath all day long. These creatures have evolved abilities that they use to survive and find food and escape predation, and they use these abilities when they have to and as much as they have to but don't wear themselves out non-stop.
In this as in all things...more is not always better. In our tiny aquariums...and even the biggest of them are tiny in comparison with a natural environment...we can't hope to approximate the huge variations in current flow that are apparent in even small streams and creeks. We can't install boulders the size of refrigerators in most of our tanks; even the largest aquarium rock won't break an extreme current flow enough to create a slack water area behind it, so it's probably a good thing that we can't recreate the torrent of a trout stream in the tank...although many people seem to want to do just that.
The most immediately apparent exception to the above would likely be fish such as plecos, hillstream loaches and others who have evolved mechanisms that allow them to cling to rocks and other surfaces in even the most extreme currents. They aren't burning calories fighting the current; they just hang on and maintain position without much expenditure of energy. They are the exception that proves the rule, having found a "work-around" that gives them a niche all their own.
I'm not suggesting that a completely stagnant tank is ideal, although for some species it isn't far off. You can definitely have a tank with insufficient water flow for some species...but it's also possible to go too far in the other direction and provide too much. Common sense and a reasonable interpretation of the way most fish live in high-current areas dictates a middle of the road approach, a compromise. In the real world, "compromise" isn't a dirty word; it's the pragmatic ideal.
How old are those posts? How do you find them? How do you even remember they existed, to look for them?