There was some question on what the big deal was about using big rods, for large fish, when a smaller weight rod can catch the same fish!
If you want to try and catch a big fish on a light fly rod or even a small tippet, please keep the fish, and eat it. The fish will most like not survive if released.
Overplayed fish, on to light a fly line/fly rod, or to small of a tippet, are stressed beyond a lethal point of exertion. You may be playing, but the fish is fighting for its life. Over-stressed fish, are more likely to become ill, and diseased (use to be into freshwater aquarium fish, as hobby). Diseased fish can pass some of these diseases to other fish in the same local. Toxins build up in the tissue of the fish, from a fish that is played too long on too light of a fly line/fly rod, and this toxin can become lethal to the fish.
I would like to think, us Fly Anglers, are of a higher class of Anglers, to use the proper equipment to not needlessly do more harm than need to catch the fish. Especially if we are required or planning on releasing the fish! If it was not that important, there would not be so many different weight of fly lines, and the respective fly rods and fly reels that go with the line. Use the correct size of tippet, for the fly being used, and for the fish being fished for. And please be a responsible angler, when it involves our public fishing waters, and the fish that reside there.
Maybe I read the comments of some member in the wrong light, but I believe it should be consider crimminal to purposely fish for fish with too light of a fly line/fly rod/tippet.