The benefit being highlighted is that the "executable code" of the system is stored in volatile memory. The same can be done for a more traditional software system.
To nitpick, FPGAs are COTS (Commercial Off The Shelf) components since a single
FPGA can be bought to be used in a huge number of different products. An Application Specific Integrated Circuit is designed for use in a single product, as the name says. A classic example were the two big chips Apple designed for the Apple //e to replace the large number of TTLs used by the Apple ][+.
To be fair, more people use the term ASIC wrong than right.
I think that's a reasonable distinction to make. I also think it's more like "firmware" insofar as it's a squishy, environment-dependent usage.
It seems unreasonable to me to cite the name "application specific" and conflate that to "single product." Nobody would debate that an Nvidia Tegra T20, for example, is an ASIC and yet it is contained within numerous products. An even more prevalent example would be any TI buck converter, used in a likely unknowable number of products.
I expect the level of application specificity needed to satisfy a particular view on ASIC varies by exposure and domain usage, which is why I think it's more like "firmware" than like "program" in a taxonomy of names. I also think that ASICs is a kind of parent group, members of which are things like microcontrollers, microprocessors, memory devices, FPGAs, and CPLDs. To draw such a hard contrast between "ASIC" and "FPGA" seems to not appreciate that an FPGA necessarily has fixed design elements (components, peripherals, etc.) to effect the function and provide more tight tolerance functionality like high speed signaling, which are limited resources by locality (only assignable within some bank of pins, for example).
The benefit being highlighted is that the "executable code" of the system is stored in volatile memory. The same can be done for a more traditional software system.