I guess I am, though I'd like to think I'm not a stickler for any rules. I fly fish for all different types of fish: trout, bluegill, crappie, bass, carp, etc. So when I get on the water I do usually have a certain type of fish in mind for that day. Okay sure, but what if I'm fishing for bass - am I disappointed if I happen to catch a crappie instead? Well no, I'm not.
I will admit that I am first & foremost a trout angler. So if I ever caught a trout while fishing for something else I'd be pretty stoked about it. What if it were the other way around: I'm fishing for trout & catch a bass? I'd still be pleased with my catch, but I guess not as much.
If I accidentally catch a fish I don't normally get on a fly, that's cool, too. For example, I've caught catfish on a fly. Since I don't actively pursue them it's pretty neat & special when that happens. The only exception to that, for me personally, are suckers. If I'm trout fishing & happen to catch a big sucker I'm not really going to celebrate that. But if I'm trying to catch suckers (try it sometime - it's not as easy as you'd think) they always seem to elude me & are difficult to target. That would be about the only time I'd be jazzed about catching a big , fat sucker.
Fly fishing, as a sport, has really grown over the last few decades. It's not just about catching trout anymore. In fact if it swims, chances are there's someone out there trying to catch it on a fly. I think that's cool - we each have our own thing. I just find it funny how we each look at it. I guess the old saying is true: "one angler's junk fish is another angler's prize". Whatever type of fish you try to fool with fur & feather have fun & good luck!!