Complex question.
There's a lot to it.
First of all "stopping power".
I really wish that term would drop off the face of the earth. If there's anything to "stopping power", beyond destroying the CNS, it comes from hydro-static shock. Hydro-static shock comes purely and totally from
speed. A wider bullet
at speed may produce more Hydro-static shock than a narrower bullet
at speed but neither will produce any at low speed. Virtually no handgun round is fast enough to reach the minimum speeds required (about 1,800fps
minimum) to produce Hydro-static shock. Some will get there, yes, but at what cost? The blast, recoil, follow-up shots, gun weight, everything is nuts in terms of SD.
Kinetic Energy versus momentum.
There's more to life than kinetic energy. Momentum is a big factor. Slow, heavy bullets have a lot of momentum. Momentum can be good or bad. Momentum is responsible for penetration. That's important. Kinetic energy doesn't produce penetration, momentum produces penetration. Penetration is good... isn't it? Maybe, it all depends what's on the other side.
Kinetic energy is what expands the bullet. It takes energy to bend metal.
You say "Please do not post about..." but that's really what it comes down to. A howitzer would be awesome for SD but the recoil and muzzle blast are a big obnoxious, not to mention the recoil and over-penetration.
In any case, the points and opinions can be argued one way or another but what CAN'T be argued is that there's a lot more to it than ft/lbs. That's why ft/lbs is the determining factor in a SD choice.