I don't rush either but I also rarely do dungeons without my partner anyway so he's always the healer. Tough turtles for any DPS that are looking to rush through for their daily rewards so they can go rush through something else or something. I'll go however fast I want, whether it's one group at a time, two, three, etc. and if anyone runs ahead because they don't like my pace, they can die, because I won't save them and my partner won't heal them.
If people want speedruns, they can use the PF. People can say I'm "being mean :c" by slowing everyone down, but it's funny that people only worry about inconveniencing the people who want to go fast, and not that rushing is annoying or boring for people who'd rather go at a different pace. This game (and every other game, for that matter) is full of people with different playstyles. You get what you get in DF, and the tank ultimately carries more weight in that scenario. If you want to go faster, be a tank.
And no, I'm not accepting counterarguments. I'm agreeing with OP about not wanting to rush, so don't waste your time trying to pressure me into changing my stance.
