Which is a funny thing: Interlaken is officially a town of 5700 people, and yet they're got two train stations receiving international high-speed trains. I guess it's really a town of 5700 Swiss and 100,000 tourists.
And the ICEs that started in Interlaken left on time. But once our train to Switzerland got delayed, I think we had to switch in Basel and take a bunch of local trains. So maybe you're right; maybe they're only allowed as long as they're not delayed.
Still, I don't understand how German trains manage to become such utter chaos every single time. I feel a lot better about the Dutch railways now.