ASIC and FPGA feasibility as GPU

Question

I've done a minor amount of research into the topic of bitcoin mining using ASICs and FPGAs, and I've started wondering:

Could these be used as GPUs (possibly specialized to a subset of what modern GPUs are capable of)? If they're so much faster than GPUs, what is preventing them from being adopted as a GPU replacement? Is it just that they are specialized hardware and simply can't perform all the tasks a modern GPU can?

And as a quick side-question: Do password crackers use these as well? If not, why?

Answer 1

No. ASICs are Application Specific, so they can't do anything else. Not password cracking either.

You can use them as an electric heater.