It turns out that graphics hardware is perfect for certain kinds of non-graphical scientific computing. Dedicated GPGPU hardware already exists, but people don't have those at home and/or on their regular computers that they use.
I really don't see the issue. GPU is specialised hardware for certain computations - faster and/or more energy-efficient. Your analogy is weird too; if a CPU is a car, then a GPU is a specialized car that can go 1000x faster under certain specialized circumstances.
That said, your original issue was with general purpose compute infrastructure on top of GPU, which can be applied to this analogy too; using the Thrust SSC to transport a container is probably not the best. Possible, but suboptimal.
It turns out that graphics hardware is perfect for certain kinds of non-graphical scientific computing. Dedicated GPGPU hardware already exists, but people don't have those at home and/or on their regular computers that they use.