It's a terrible feature, I've always said so.
But we already have banish noble which covers almost every case of wanting to eject someone.
Because any intra-realm conflict would probably be very hard to code and balance.
Like looting his region... how does this work? A realm can't loot its own region. Say you remove this restriction for that particular region... well, you can't loot when the realm has rallied defenders. In this case, you are of the same realm, so you are naturally a defender, so once again, the mere fact that you have a unit able to loot would prevent your unit from being able to loot. Say you ignore your own unit for this restriction, then... well, what if a peer wants to come loot with you. Then his presence is stopping you. Say you also exempt allied nobles from counting... then what about exile nobles? Are they able to defend against looting? If so, can you fight them? How? Can't arrest them if they have a unit, and even then, you can't arrest nobles except if they are priests of an enemy realm. A realm usually cannot fight itself, save for in a rebellion. Also, if you loot so much as to create peasant militias, will they just stand by and ignore you afterwards, due you being of the same realm as you?
The only existing mechanics that would more or less approximate the things you have said are the outright rebellion mechanics. If the ruler could force a rebellion of sorts, then maybe there could be the desired power struggle. But if there's the normal timer, then it's ridiculously easy to abuse. And if the rebels don't have access to some form of recruitment, it is again ridiculously easy to abuse. But if they do, then you've essentially just created a different realm, which leaves you to wonder of a forced secession wouldn't have been better off. But that comes with its load of complexity though.
