Excerpt from "A Strategic Analysis of the Use of Mega-Scale Vehicles in the Great War" by Jaelyne Casdy
[...] While both the Concordiat Continental Siege Unit and the Eternal Odyssey Strategic Assault Platform (better known as the 'Monolith') were fully capable of assembling even super-heavy combat vehicles from scratch thanks to the massively increased scale of their Internal Fabrication Units, this was not their intended function. Rather than rolling factories, strategic planners of the day envisioned these units as mobile supply and command points, repairing damaged vehicles and constantly manufacturing ammunition, fuel, and other supplies for allied forces.
The idea that these massive constructs were intended for support rather than direct conflict seems paradoxical to many, especially when one considers the massive firepower they were also equipped with. It is less surprising, however, when looked at from a more practical perspective. For all their power, even a mega-scale vehicle can only be in one place at a time. As they were never available in the numbers required to fully secure a planet on their own, lesser units were required to ensure flexibility and to secure areas the mega-tank had already pacified. As the fragile fabrication engines normally used to keep such forces supplied often made easy targets, the idea of a source of repair and supply that could only be threatened by another mega-vehicle or heavy orbital bombardment was an appealing one.
The Monolith is especially indicative of the idea that the later mega-vehicles were designed for support rather than front-line assault. The last design released prior to the end of the Great War, the Monolith's most dramatic innovation was [...]