When I was involved in high-energy physics (doing some pretty pedestrian software stuff), CERN switched from its beloved Hypernews system to something based on MS Sharepoint. Everybody was baffled about why they would do that and hated the new system.
It seems like Hypernews was only turned off in 2021, much much later than planned, but they did do it.
The experiment SW is a lot like the buildings and labs in every physics department I've been to: everyone is on a separate 3-5 year grant cycle and as such is contractually obliged not to push for newer infrastructure. People stick to the same software/lab until it is discontinued/condemned.
It seems like Hypernews was only turned off in 2021, much much later than planned, but they did do it.