This article I found explains clearly the advantages and goals of this new cartridge. Comparing the .45 acp to this is like comparing a moped to a dump truck.
https://www.loaddevelopment.com/8-6-...-8-6-blackout/
Some notable excerpts...
"Why a New Cartridge?
Yes, it feels like every week someone is just necking some other cartridge up or down and “bringing out a whole new cartridge”, but this time, it is really a game-changer. The 8.6 BLK is not just an improvement on previous designs or a wildcat, it changes what was thought best for hunting cartridges and tactical military cartridges all together. It shows that large long bullets can work out of small cases, and even better, high energy effective hunt kills can be made out of short barrels, even at what would be considered long range distances for hunting."
"When loaded with a 210gr Barnes TTSX bullet at 2450fps from the short 12.5″ barrel, you only have around 1.4 MOA more drop at an incredible 300 yards than a usual 308 Win with a 168gr bullet would have, but with a whopping 300 ft/lbs more energy on target, and that all from a rifle short enough to fit in your backpack. That is just to show what it can achieve, however we doubt many people would hunt at such long range with it."