Because you are ignoring the argument. To cross the void, its 2 phases:
1. Crossing it
2. Maintaining structural integrity
And the latter is a thing that doesn't show up very often in Fiction. On top of my hand, named examples include Stormbringer in the Elric saga, and Frieza in DBZ.
But this is important, as once you have crossed, you need a Badass Wizard to guard your logistic wagons, or you can't have the gear existing. > doesn't really hold up since one requires loads more training than the latter
? Are you stupid?
To even have laser rifles, you need all the technology and the power sources to create those. And once that energy is spent, that needs to be replaced.
If a Adapt can become a demigod in a lifetime, remember that the tech tree to get laser rifles involves centuries of advancing tech. Because your argument forgets the vacuum of such arguments.
Often its a setting where things are not isolated, so by itself factions share technology, and are around the same level. But KSBD isn't such a setting. Once you cross the Void, you lose most of your tech tree. Power levels means smaller stronger armies are important, and for mass conscripts suddenly you need logistics. Logistics turns into a mess once technology isn't powerful enough to keep up with Kung Fu wizards.
But there is another argument you are also forgetting: Knowledge IS logistics and technology.
Training adapts is on this tech tree, but unlike tech stuff it transfers fine in the Void.
Meanwhile even Laser Riflemen quickly needs several months of physical training to stay fit, and the same time a lot of training to even stay in formation to make their weapons useful.
Its the dreaded curse of knowledge and training, that makes people think "bandits roaming the countryside" is even a thing in Post Acopalyptica or Medieval Kingdoms.
Bandits where simply unable to keep up with a state fielding armed forced with state of the art gear, and this continues into Kung Fu Wuxia.