I 100% agree that a fishery can be ruined by overfishing, more specifically, over keeping. The ambiguity of "fished out" is the problem. No, you will not remove ALL of the bass. But, you do not need to remove all of the bass to ruin a fishery. Slot limits work for a reason, they protect the fish that sustain a fishery. Not all fisheries need the same slots protected; current population, geographic influence, intended consequence all play a role (and others obviously).
If you take two large ponds that are identical, you could manage one for "lunkers" and one for "lots of catching bass". Over a period of years, if you follow the guidelines, you will see a significant difference in the fish caught in each pond. You wont catch nearly as many in the lunker pond, but those you do catch (on average) will be much larger than those in the more highly populated pond; especially notable will be the big fish of the day. Conversely, if you want to catch a lot of fish - the other pond is your best option. Granted, pond management should go deeper than just which bass you keep and which you remove - but the impact of which bass are managed is key.
Why would we expect anything different? Consider a lake or pond with only bluegill and bass (Not realistic, but shows a simple example). If you remove too many bass, the bluegill population will explode. One may initially think, ok great, more bass food. But, we often forget the bluegill need to eat too. And they will chomp on baby bass. So now we have pulled out the large bass which would eat the bluegill. That also means we have removed many of the bass that would be breeding. So already we have fewer bass, and fewer to reproduce. Now, add in that we have MORE bluegill and they are eating MORE baby bass. Now you are left with less mature bass, less fry, and more predation on those fry which do exist. It's easy to extrapolate the impact to that fishery. Smaller fisheries, naturally, are more at risk - but any fishery can be impacted to some level. Now all that said - this is oversimplification, but I think it easily illustrates the impact we can have on any pond or lake.