The real bitch is you also need to replicate both the software and convince some large projects (eg, pytorch) to use and support your implementation, and it’s just all rough, very complicated, very fine-grained stuff. The hurdles here are very high.

And if you fuck that part up in any one of a dozen places, no one will use it, because the adoption cost is too high, or your implementation was 20% slower and so everything costs 20% more to use and no one uses it.

This is why you see things like TPUs never really damage NVIDIA, but why basically everyone is focused on open standards and open software. Basically the entire tech industry is using this approach as a way to slowly peel away the layers of this software until enough has been removed that NVIDIA can no longer use it as a moat.