“Which is more likely: that the irrevocable laws of the universe have been broken, or that you are somehow mistaken in thinking them so?” – Dwarf engineer, moments before a massive reactor breach shortly after the Convergence
Erff, the Grey World, has long been devoid of anything resembling free magical energy. As you may imagine, the Convergence has not been kind to it. A majority of Erffly devices simply fell apart soon after the worlds combined, a result of magical flows getting into their carefully calibrated parts and generally mucking things up. Many simpler devices still work, of course, but anything electronic is unfortunately kaput, and likely for good. (Top Dwarf and Dragonborn engineers are working on the problem, often working in concert with Tiefling technomancers, but progress is slow and not looking especially promising at the moment.)
On top of the rest, much of the geography of the Grey World is still simply lost in space somewhere, and the great cities and contraptions of Erff with them. Whole buildings have been known to sprout in chaos pockets and the domains of some of the more permissive Powers, but as a whole the Erfflings have had to make do with rebuilding.
Their knowledge of architecture, engineering and, perhaps surprisingly, the natural world is still quite valuable. Even barely-educated Erfflings find their vast stores of knowledge to be in great demand. The dimmest, most pop-culture obsessed Ork suddenly finds that he or she has something to contribute in an intellectual field, and that has been a real eye-opener for some.
Of course, Erfflings are practically worthless as mages and spellblades and whatnot, although not through any innate failing of their own. Young and recently born Erfflings are as capable as any race of learning spellcraft, no matter how impossible their elders find it.