If someone in my group is slower or not acclimatizing, does that cost me my summit?
Can weaker or unacclimatised climbers in my group hurt my summit chances?
Sometimes, and how much depends on the peak and on how the operator staffs the climb. A well-run group expedition is built so that one climber turning back does not end the day for the rest: there are enough guides for someone to go down with them while the others carry on.
The full answer, kept up to date: Will weaker climbers decrease my summit chance?