Firmly plant in your mind these two facts about the setting:
1. Rock gnomes can make tiny clockwork devices.
2. These devices have not been reverse-engineered on any grand scale such that they are commonplace in the world.
Now instead of thinking about why these things can't both be true, start brainstorming how they might, could, or may be true. Then pick one or more of those reasons, go with it, and don't look back. This is a good exercise in imagination for almost any facts that might seemingly come into conflict when thinking about the setting. When we stop thinking about how something can't be, it becomes easier to see how it could be.
An easy one might be that this gift of artifice is divinely-inspired, something imparted only to rock gnomes by Nebelun the Meddler, a lesser god of inventions and good luck. Other races don't have that special something to get the clockwork machines to work, even if they can replicate them mechanically. From his workshop in the Golden Hills, he can see all rock gnomes tinkering away on their inventions throughout the multiverse. Those creations that meet with his approval begin to click and whir and spring into motion.