Oh nonsense.
The "Quiet keys" and similar devices have been around for at least 150 years; many pianos did, and still do, come with one as standard equipment. Its also how the soft pedal works on square grands.
This said, this particular brand is more expensive than most - I paid around $60 for mine, but it was a bit harder to install. The installation, once completed, I feel *MAY* be better than Quiet Keys, but as for results, they are the same.
Understand that this method of muting is only partially successful - the higher notes are totally muffled unless you really pound on them, the lower notes are louder the lower you go for the same amount of key force.
I like mine, it does what I need it to do - not drive my wife crazy when I want to play and she wants to watch TV. It also has a really nice, soft sound.