Either way, they end up having to fight on a thousand little battlefields all over the place and likely do not have the interest or ability to fight each and every one. This is the sort of thing that can tie up legal teams for years and drain reserves in no time.
I was involved in a mass-arbitration last year. The NDA bars any details from being released for 2 years but in the meantime, we can say we reached "a resolution, not a settlement" in the dispute.