Once the horders realise how boring, repetitive and mundane real estate capturing is, they will venture out to become one of the higher order of adrenaline duel junkies.
They just need the encouragement.
Sadly, that only works for a few, for many it seems, the shear thrill of ruining another's fight is all they are after.
An extreme example: there were a few people who would wait in the DA for people to get into private 1v1s on the side fields, then up with the sole purpose of ruining it for the other two people.
In the MA, there are several people who famously wait for others to get in fights, then swoop in to deny either player of the satisfaction.