Partly, given the maximum power you can pull from USB (500mW anyone ? )
500mA is usually regarded as the maximum current from an otherwise unspecified USB socket, that's 2.5W, not 500mW.
This device further limits it to 2.25W output, at 15v after losses you're looking around 110mA
As for the utility of such a device.... eh, not for me.
Just get an LM2577 based SEPIC module for a few dollars, replace the pot with a 10 turn panel one, and wire an old 2A usb power supply on it.