The video is essentially an argument from the software side (ironically she thinks the hardware side is going pretty well). Even if the hardware wasn't so hard to build or scale, there are surprisingly few problems where quantum algorithms have turned out to be useful.
It is tough to beat classical computers. They work really well, and a huge amount of time (including some of mine) has gone into developing fast algorithms for them to do things they're not naturally fast at, such as quantum chemistry.
The video is essentially an argument from the software side (ironically she thinks the hardware side is going pretty well). Even if the hardware wasn't so hard to build or scale, there are surprisingly few problems where quantum algorithms have turned out to be useful.