Please don't give abusers any ideas.
And expect to get kicked if your caught doing said action....minimum reported.
Private party is one thing..but in roulette/DF's? No way.
Vue imprimable
AFK timer is there for a reason. if a person leaves its more likely they will be replaced and or the party will abandon the instance, freeing up space for another party to use. it's all about efficiency.
You seem to be a busy person OP. You probably don't have much time in your day to play due to your IRL responsibilities. Would you REALLY be ok with spending a good chunk of your limited free time waiting for someone to deal with their own issues in the middle of a game?
It's the personal responsibility of the player to ensure they have the time to finish what they queue up for. When the unexpected happens and you'll have to be away for more than 5 min or so, let people know and they'll probably eject you so you don't get a penalty. If you're going to be gone for a very long time or aren't sure if/when you can make it back, be polite and leave after saying "sorry I have to go".
I don't have sympathy for people trying to play group content in MMOs when they know there's a really good chance they'll have to AFK and inconvenience the rest of the party. Do some of the many solo activities the game offers, queue as a pre-made with people who understand and know what to expect from you, make sure you have back-up to handle the issues if you can arrange it, or play something else that won't impact other people. No one's telling you not to play just because you have responsibilities but at the same time your obligations are not our problem- it's up to you to figure out when and how you can play without needing to go AFK for extended periods of time. That's just part of being a responsible person and a considerate player.
The only time I've ever run afoul of this was when I was running an adventurer squadron dungeon, and someone called me away for help on another game. Getting back to find out I'd been kicked out of the dungeon was sad, but I'm not going to ask that they remove the feature.
I'm mildly surprised it's an actual thing, since I'd drop from an actual party (or be kicked) if it took me that long to do something.
The servers can only handle a certain amount of instances running at the same time. Anyone who had Stormblood early access and got stuck on Raubahn Extreme or Pippin Savage can tell you that(and likely complain a ton while they were at it). So the inactivity timer in a solo duty(whether quest initiated, undersized, squadron, or PotD) is there to make sure "unused" instances keep being freed up for the rest of the players to use so that we dont get to that cap. For groups they probly assume we'll kick the AFK person after some length of time(its on the kick menu afterall). The timer then prevents one specific type of griefing(someone goes afk and their friend in the party blocks kick attempts forever).