I don't think the bottom-up model denies the importance of the top-down architecture. In practice, you have pressures from both sides. You need to explore what'

I don't think the bottom-up model denies the importance of the top-down architecture. In practice, you have pressures from both sides. You need to explore what's possible at the bottom but also respect what's required from the top. And they are complimentary. You explore what's possible from the bottom and then you need to adjust how you should organize those possibilities according to the requirements from the top. At the end of the day, as everything else in the world, it's all compromise.