One problem with NIP-72/87 is that a group is owned by someone -- whoever holds its admin key -- forever, it's not an aggregation of members and messages, but a personal property that can't be handed away.
However it happens all the time, for example, on Reddit, that some members are unhappy with the current administration and want to fork the group. It has also happened to me twice, in two small Telegram groups (~10 and ~100 members), that the group owner became unresponsive thus the group lost all its moderation capabilities.
In NIP-29 this would be fixable by just moving the group to a new relay, which could be done gradually while keeping the old id and history.