Vent peanut, it helps to once in a while. Native fish can be kept in a fish tank if they belong there IMHO. That means same temperature requirements, same space requirements, not confined to fresh water. Salt water fish often times don't leave a patch more than 1000 cubic feet in area. Putting a fish like that in a 100 gallon reef tank isn't going to be like taking it out of it's natural environment. Although I know there are exception they happily survive in fish tanks of proper size. The point is you aren't going to go out and get a halibut to put in any size tank salt tank. You also should not go out and catch a carp and put in a freshwater tank, if you are educated.
The real problem is LFS don't care about anything but the bottom line. And I don't mean the ones like I have seen where the owner has 12 staff members that spend 100's of hours maintaining their tanks. If I can acclimate MTS from my local lake to make them safe, I would go out and get them. If I had a species of fish that I knew would be well at home in my fish tanks I would probably figure out how to acclimate them and go out and get one, if it was legal.
I actually do know of a fish that lives in brachish tidal water that if I had a tank to put it in I would but it only gets to be 6 inches long and would be more than happy in a tank that met the fishes specific requirements. The fact is I will never be able to do so because of the fishes natural environment so in the estuary it will stay.
Just be sure that you research a fish before deciding it would make a good pet. You would do the same for a wild mammal that is often kept as a pet, or at least I would hope one would. After all, just because a cottontail often makes a good pet doesn't mean a wild one will.