Throughout high school our team had to race twice a week for most of the season: once during the week for "league meets", and again on the weekend for invitationals or championships. Our coach instructed us to race all-out for every competition regardless of whether it was a league meet or invite. By the end of the season we had probably done about 40 or 45 miles of racing throughout a season, which is probably too much for kids running 25 miles per week anyway. Throw in a couple of workouts each week, and we were totally cooked by November.
Many of the schools we competed against did not race the league meets during the season, either by removing the top runners from the starting roster or having them do workouts during the race. Some schools were interested in the league rankings and may have employed strategies to do well on it, and others completely disregarded the league and focused on performing at invitationals. So, I'd say there were plenty of times talented runners in my league intentionally "tanked" league meets to some degree.
My understanding is what I explained above is widely done in high school XC.
The college I attended happened to dominate our conference by a decent margin. Every year at conference, our coach would instruct athletes to run well below their peak performance, yet well enough to win the conference title. While the title was a nice thing to have, our coach's main interest was in peaking for regionals and nationals. I understand many college programs employ similar strategies here as well.
I'm not saying what Princeton did was the exact same as my examples, nor should it be accepted. But maybe it's a symptom of a larger problem in general with XC? The sport is so fragmented that there's no "main" objective that every team automatically strives for. Some teams' goal is to do well on their conference, others simply to set fast PRs, others to make nationals, others to perform well at nationals, and the list goes on...
Other sport leagues such as the NFL have objectives that are clear and are typically universally accepted by each team: make the playoffs, win the championship. Not the same with XC. There are too many objectives and each team seems to have a different goal in mind. Ultimately it creates results like this, where a team is forced to perform at a competition it's not prioritizing. It makes the competition uninteresting and pointless.