I'd say the working relationship is the important thing. (yaay, synergy!) Naturally TSMC knows their tools and processes, works with product companies (nvidia,

I'd say the working relationship is the important thing. (yaay, synergy!) Naturally TSMC knows their tools and processes, works with product companies (nvidia, AMD, Qualcomm) to actually implement their design on the target process node. And at the same time works with the various tool vendors to refine the process, the tools themselves. But as lately we saw it's increasingly impossible to do it "alone", both Intel and Samsung works with many-many vendors. (Intel - among others - funded the push for EUV by buying ASML equity in 2012.)