Yeah player clan parties are very lacking in any function other then just troops holders in a perpetual army with you. Any other gameplay besides giant army blob they become a problem. I submitted a bug report because I found that when disbanded they will just go to another clans fief (in another faction!) and dump off all their troops too, instead of going to your own clans fief like they should. In past versions they would go to your nearest fief and deposit troops when disbanded, so this was another use and if you liberated a large amount of troops you could make a party on the fly and disband it send it to your nearest garrison. Now they somehow ruined that with thier updates.
I feel like it's a huge miss read that TW either disagrees or doesn't see how much players want to have some control over what their own parties do and don't do.