It seems wrong to call it a "job of customers". It's like you wrote a Bitcoin client which didn't verified hashes of transactions, "trusting" everything. Or like serving a website with login feature supporting only HTTP, not HTTPS. It is a very basic feature of whatever software would connect to such services.
I don't know how developed is it now, I'm not associated with the startup shown in any way. It's mainly a question to them. However, in terms of wider industry, in general distributed high-performance GPU(-like) computing "for everyone" is in its infancy. 99% of what was already done up to this point was targeted to people who would both buy and supply power "in bulk", not "in retail". Perhaps with a little exception of several excellent projects like Folding@Home and other @home's.
