I just created a bug report, your argument is also absolutely correct, so I would appreciate it if you could post it there.
This is a rather specific case, but after considering many aspects, I consider it a bug. In update 1.4.4, all monoliths gained vanity accessory functionality, displaying an overlay when placed in vanity slots. The Echo Chamber, added in the same update, also qualified for this change, which I consider a bug.
Firstly, the Echo Chambers, which can be crafted, have the same functionality as the Spectre Goggles, which can be purchased. However, the Echo Chambers work in the vanity slot, while the Spectre Goggles only work in the accessory slot.
Secondly, unlike all other monoliths, the Echo...