A name for that strange time I was in a room of ~15 people chaired by me, who unanimously decided that PHP should be used for the website, made by volunteers. Yet when I asked individuals afterwards, none of them had wanted PHP, and only one or two ever used PHP.
They chose it because they incorrectly thought that's what most people wanted, and they preferred to go along with their perception of group view so readily that nobody revealed their own tech preferences, despite a long discussion.
It wasn't a compromise, because that would start with people knowing each others' preferences, then compromising.
It was more like a bad default based on incorrect beliefs about each other.
The strangest part, for me, was realising that this happened despite meeting for a good hour discussing alternative options, with several professional webdevs in the group. The groupthink effect is powerful!
The effect of the group decision was not what people in the group had hoped for. Instead of producing an attractive common interest, it resulted in few volunteers, because everyone picked a tech choice they were not interested in working with themselves, assuming it would be of more interest to others.
Very nice. It reminds me of a https://en.wikipedia.org/wiki/Keynesian_beauty_contest : "a beauty contest where judges are rewarded for selecting the most popular faces among all judges, rather than those they may personally find the most attractive".
The Abilene Paradox is used to describe an unhealthy consensus.
The problem is, is that a hallmark of a healthy consensus, is that no one is really happy with the decision, and a hallmark of an unhealthy consensus, is that no one is really happy with the decision.
The same happened to me last year, on a company trip people voted to not go to a bioluminescent swimming, but when I confronted them everyone was really wanting to go. We ended up going (I can be a bit pushy), and everybody loved that experience.
"In one famous example, Thomas C. Schelling shows that a slight-but-not-malicious preference to have neighbors of the same race eventually leads to completely segregated populations."
https://en.wikipedia.org/wiki/Abilene_paradox