There’s no real logic to them only being in PvP, Trials and Explore either though, is there? They are not a standard part of the game, and if one was thus inclined, one could make cases for them being disruptive in all those scenarios. If it made sense, they would only appear in battles relating to the kingdom they are from.
Anyway, no one was asking: why can’t I get everything from everywhere. I was commenting that a change that was made because people complained could have been solved more simply by leaving it as it was, but just making the battle crashers appear in more places/more often.