I think integration was always going to be hard and most people who understood the problem knew that it was going to be hard/impossible but they went ahead with it anyways.

At the time they were talking about integrated compute units between CPU and GPU, mapping GPU register space into CPU address space, linking/unlinking CPU and GPU pipelines, etc etc. And the CPU and GPU teams would be working on this while also having to produce top-shelf stand-alone CPUs and GPUs to fight on 2 separate fronts against entrenched and capable competitors. It didn't really seem possible or even desirable at the time.

I also don't understand why having a GPU would improve their chances with console vendors. Those vendors could have still selected AMD CPUs but cut separate deals for the GPU with other companies. This is a business AMD is already and was already in. They do this in all sorts of markets like network switches.