Well I'm not sure on this mechanic in itself. The thing I get from this mechanic is that they are ingame items which replicate movess and that they can't be used in the overworld. Now to be fair, they most likely can't be used in official gym matches because let's be real if they were to be used once, (In game) Ame would be informed. Ame would then crack down with new rules. Even then I wouldn't really be sold on this mechanic. The reason for this is not story/morality driven but rather this. The items directly empower the player in battle. One of the big complaints is that the players have little control in the overworld. You can't stop Garchomp, you can't stop your ruby ring getting stolen (twice), you can't apprehend villains, you can't move grunts/people, you can't destroy some small gate, ... . This is compeltely in contrast with battle where the player has full control. Now these items directly empower the player more, they have actions that affect pokemon but they can't use it outside battle. This widens the difference between overworld and battle even more. "Basically I can tase a tyranitar but not Fern/Taka/Grunt...?" "Or a use shield generator to protect Kiki?" So much options which can't be used.