Both? Theoretically amazing hardware that just needs the magic compiler to work well is a well worn path in the hardware world (The itanium being a notable example). A design can be impossible to compile well for and very hard to program manually if it hasn't been developed well. Equally you can indeed have a bad toolchain for that hard to use design making it even harder to get the best out of it.

I'm thinking of the Sony Toshiba IBM Cell processor. In the end with experience you could deliver impressive performance and the lessons learned proved to be valuable on any multi core system. But everyone knows the reputation that the PS3 had and certainly in retrospect it was challenging to say the least.

Nah, the issue with PS3 was everyone coming from a specific set of instructions and having, that, hard wired into their brains. Yes, the cell processor did things differently but it was us engineers who had to learn to think of a world beyond x86. This was a good thing. It let us learn. And when Arm came around, we were ready.

Very much agree. It was a positive experience.

It doesn't matter. You have to get both right or you go out of business.

(And then your IP is thrown away so the next startup also has to get both right...)

Yeah, merely asking for posterity in case someone wants to iterate on it. The dev tools need just as much attention as the hardware. Sometimes the community can surprise you. Take fritzing for example. I think the hardware design is novel but to benchmark it fully requires dev tooling that knows how to utilize it all, and in such a way that it abstracts those details from the average developer.

A good example of this is abstracting SIMD instructions for vector multiplication, or CUDA with torch. Normal people don’t care how it’s done, only that it’s done, as fast as can be done.