FSR is an upscaling solution that can give better quality and sharpness than naive nearest neighbor. That's the whole point. This doesn't require extracting game files because it is fast enough to operate live and can operate on screenshots.
It is not exclusive to applications where performance needs to be increased, otherwise people would just use nearest neighbor.
I'm saying this as something people who complain about blur should try, because the sharpening filter can help with that a bit.