This is about modern PCR, which is already optimized a lot compared to early PCR. And if you're in a "normal" lab, everything around the PCR, all the handling and preparation will be such a large chunk of time that improving the PCR time alone doesn't really matter that much.

In a very automated, high-throughput setting I'd imagine that parallelizing the PCR would be the best way to increase throughput. There probably isn't that much potential in speeding up the time compared to just multiplying the number of reactions. Which is part of the point of the article.

Regarding the cheaper lab instruments, I'm not quite convinced by these ultra cheap examples. Many lab instruments need quite a bit of precision and reliability, and I would be suspicious that the cheap examples here could compete in that regard. Even PCR needs pretty exact temperature control across many individual reaction vessels. Of course the margins on lab instruments are likely enormous, and there should be plenty of potential for cheaper ones. But I don't think the ultra-cheap DIY stuff will convince people, and it'll likely also fail at the purchasing process anyway for larger institutions.