Chapter 402: Holy shit, an Emperor-skinned succubus!
Due to a sudden Warp Storm, many alien ships were swept directly into the Sea of Souls to wrestle with demons before they even had a chance to flee.
During such an inconvenient time for travel, the three legions chose not to court death by attempting a return voyage, opting instead to clear out the remaining aliens in the Vigilance system while resting and rebuilding in the aftermath of the disaster.
Although the Star Gate network was gradually being laid out, with the largest Cadia Star Gate right nearby, the vastness of the galaxy meant that distances which appeared small on a star map were, in reality, anything but short.
The primary method of travel for Imperium of Man ships remains Warp travel; much like taking a high-speed rail from home, you cannot simply step out your front door and be at the station—whether walking, cycling, or driving, you must reach the terminal before you can board the train.
This is why, even with the Star Gate network nearing completion, Blackwatch remains the Imperium's logistics leader; compared to the Webway, the transit speed of Star Gates is still too slow, not to mention the distance required just to reach one.
If you ask why they don't choose to build the Webway on a massive scale, you must at least have the materials to do so; the existing Webway passages were built by the Old Ones, who exhausted the strength of their entire race over countless eons to construct them.
Setting aside the lack of materials, time itself would not permit it; even if the Imperium showed the slightest inclination to build Webway gates as they did ten thousand years ago, even the seemingly "curve-loyal" Kobold would not stand for it, as this would