Recriger, I've been doing this for over 45 years, and am still learning, so you may only be partially correct. Fly fishing & tying is like life, an ever evolving endeavor.
I have to agree with all the above. I'm not a reloader, but am a lure maker too.
You could get very precise with weights, however IMO it's not a necessity. I'm to the point of just knowing how much weight to build into a fly, and don't think a lot about it.
I've learned that with lures such as jigs, the advertised weight is usually not the actual weight, (example, most 1/4 oz jigs are not) so rather than get concerned about actual weight, I keep things simple. ( I have a jewelers scale so I have weighed jigs & flies!) When I need deep, I tie heavy, and use appropriately sized equipment & leaders. Very much agree with going heavier on the entire leader & shorter as I increase the weight. You do have to keep everything working together properly.
I've fished for Smallmouths quite a bit with a 6 wt, but now have several other rods I can use, both lighter & heavier. Another side affect of the many years of being involved in the sport. Just as with other types of tackle, one size does not fit all, and doesn't work best with all size or weight of the flies. Wind resistance is another problem as has been mentioned by gator!
It could be like trying to cast 1 oz lures with an ultra light spinning rod. It can be done, but not the best combination.
What gator said about using unweighted flies & sinking lines works too, as you're simply relocating & redistributing the weight. But, sinking lines come in many types of sink rates, and even various lengths so, a specific line may not work for you in all situations, so you'll end up adding additional lines to again fill the need.
I actually own several sinking lines of different configurations & still add weight to most of my sinking flies. I can usually figure out some combination that will fit the situation, but not always.
I'm one of those who do feel that bigger flies are more often better for bigger fish. But, size of the fish will be relative to the waters being fished. I've fished tiny streams with a 3 or 4 wt where and average fish is 8" and a 12" Smallmouth is a big one, so a size 8 or 10 fly may be "big". I've fished for LM bass with a 10 wt, and use it to cast rabbit strip flies that may be 8 to 10 inches in length, or 4 inch weedless flies that are cast into really heavy cover.
A 2 lb LM is average in the rivers I fish, and a big one may be 5 lbs. I don't need a 10 wt for the size fish, I've caught plenty with a 6 wt, but do need it for the flies I use & for the cover being fished. Plus, I fish in tidal waters, where there's the possibility of catching Striped Bass, which are often much larger than the LM bass. So again, selection of fly size & equipment size are meant to work together, and not always for the size of the fish.
In most streams I've fished for Smallmouths, my usual fly size is one tied on a size 2 or 4 hook, and generally about 3 inches in length. I'll fish them using a 6 wt. Even on tiny streams with a 3 or 4 wt as I mentioned before, I'll still use a size not smaller than an 8 most times. Smallmouths will eat tiny flies, but they're not trout, they tend to eat bigger things than trout, although I feel trout do also, more so than given credit IMO.