To me quiet luxury maximizes the relationship between owner and object, rather than noisy luxury, which muddles that relationship by bringing in the outside world/observers.
So quiet luxury=owner and cherished object
Noisy luxury=owner, object, outside world/observers
The latter brings in a "third wheel," if you will, on, say, a romantic date.
Noisy luxury is ok, but it is a different relationship between the owner and object than quiet luxury.
Cheers,
John