For people to choose something it first have to be a realistic option. Berlin is much more established as an international and "tech" city. You hear about people moving there all the time. For whatever problem you'll face there's bound to be someone else who has done it. When it comes to moving you don't want to be a pioneer and spend thousands of euros finding out if it's doable and ending up not liking it. Being in the same boat as other people helps with that uncertainty.