That's the canon explanation, actually.Mechatrill said:
The real killer, however, according to Wildbow, is maintenance. An example from Wildbow, is the army buying power armour from a tinker. During it's first engagement, a hole is blown into it, and the tinker is unavailable for repairs. Since all the vital internal bits are intact, they patch it up themselves, only now it moves jerkily and overheats.
Then they try oiling the joints to fix the movement problem, and the whole thing dies. They call in the tinker, and it turns out the patch job threw off it's balance, causing parts to overwork and overheat. And the oil they used was the wrong type, and accidentally applied it to the heat vents.