That's also called "constructive feedback" or "having something useful to say". OP offered his thoughts on the best cases where this technology could be applied while explaining how Parkinson actually works and how this limits the usefulness of this solution. If this is "such an HN reply", then this is also the kind of reply for which I come back to this site.
Not that the spoon won't be useful in many situations, but I've seen other appliances - walkers with laser cues to try and improve the "freezing of gait" phenomenon, stomach tubes to try and get over the fluctuating levels of medications, all tried. They're nice, they're not invasive, they don't get used.
PD is complicated enough that solutions need to get a hold of the "big picture". For ET, it probably would have more of a role but still, what about writing, handling complex controls, etc? The spoon may fix a limited set of problems in all of this, but the bigger picture is what will get a bed bound or wheelchair bound patient back on their feet and doing all the things they need to do in daily life. There are better solutions available for this than just the spoon.