But it doesn't! The result will always be a crapshoot. You'll get sound but for how long and how good will it be??
I'm just going to agree to disagree here. It most certainly works, and you're even saying it does.
I can only use myself as an example.
Aggie DB-359 (200w all tube head)
Aggie GS410 (8 ohm)
Aggie GS115 (8 ohm)
So the 15 was getting 100w, and each of the 10's were only getting 25w...right? How long did I get sound? 3-4 hours a night, 3 times a week, for about 5 years. How good was it? One of the better tones I've ever had. Never once gave me a problem.
Would it have been the same if I were running 1000w amp into it? Why yes! I ran my GK 2001RB bridged (1080w at 4 ohms) into those cabs for a solid 4 years after I got rid of the DB-359. How long did I get sound? 3-4 hours a night, 3 times a week, for about 4 years. How good was it? The best tone I've had, just as good as what I have now.
I'm sure it would have been better with 2 matching 4X10's, but I didn't have the scratch to get one at the time, so I got by with what I had.
So I feel like I can say with absolute certainly, it works.