This is an important generalization, but there are also many counterexamples in our use of biotech in agriculture, medicine, chemical production, etc. We can't design a custom cell, but Craig Venter can create a new 'minimal' genome from raw feedstuffs by copying from nature, and then add further enhancements to it. We produce alcohol using living organisms rather than a more efficient chemical process, and so forth. It looks like humans will be able to radically enhance human intelligence genetically through statistical study of human variation rather than mechanistic understanding of different pathways. Creating an emulation involves a lot of further work, but one might put it in a reference class with members like the extensive work needed to get DNA synthesis, sequencing, and other biotechnologies to the point of producing Craig Venter's 'minimal genome' cells.