You can think the rng loot system for that. Since catalyst and strike exclusives drop solely from boss/end chests, and drops are solely rng based, the faster a player can complete a strike, the sooner they get to roll the dice and the sooner they can either stop farming or hop into the next strike. There's no incentives to kill mobs and taking your time clearing mobs only means taking a much, much longer time to farm your drops. When it can take literally hundreds of strikes to get a single drop, and that's if you even get one, no-one wants to spend 20+ minutes for one roll of the dice. I personally don't care since, from my own experience, most "speed runners" will slow down after they get slaughtered once or twice or, depending on the strike (infinite forest strikes), I'm right there with them. For me it all comes down to what my team wants. If I feel like they're trying to just run past everything, I'll run with them. If they're taking their time killing, I'll take my time as well. If we are running, I'll stop and pick off snipers or high threat targets before I run through and that's usually enough to keep my teammates from getting picked off as they rush through. The fix for this would be something similar to nightfalls, where the higher your score the more likely you are to get drops. The increase to drop rates would need to be substantial, however, in order to provide enough incentive for farmers to want to take the time to clear mobs. If Bungie were to do something like this, and they pulled some crap where drop rates with low scores are 1% and drop rates with high scores only go up to 1.5% then obviously there would not be enough incentive for speed runners to slow down. Maybe something more akin to low scores get 1% and max tier scores get 10%. As prestige nightfalls are, from what testing I've seen posted anyways, the difference in drop rates between low and high scores is so minuscule that most speed runners can't be bothered to slow down. A score based system that increases drop rates too substantially would of course lead us back to the issue vanilla D2 had, where most players had all the gear they could ever want by week three. The system would need to be moderated and tweaked which is where the biggest problem arises; Bungie's inability to make even minor game adjustments more than once every three months. >.<