[2020] Do we know any official reason why PvP/WvW track chest rewards with armors and weapons do not stack?

For example, I have several Triumphant Armor Boxes from WvW which I do not want to open right now and each of them takes separate space in my bank.

On the other hand there are a lot of PvE "select your reward" chests (for example: boxes with armor like Carapace or Bladed) which have no problem with stacking.

Is there any official response to that "why"?