*Some of the loneliest older people I know live in retirement flats, and as a social worker I know a lot of them.
They aren't generally full of sprightly folk in their 70s and 80s doing university of the third age and sitting out in communal areas playing dominos etc. That's the image these places like to sell but it's rare that it's true.
It's mostly people who have started to struggle a little at home and families want to make them safer. So they move them to a box with a huge service charge away from familiarity and communities. It often makes them more isolated, but safer.
There's usually the same issues there would be at home otherwise, they still have to prepare their own food but with facilities they are unfamiliar with, they have to work out how to use new door entry systems etc.
People just tend to sit in their flats, watching TV while family or carers pop in and out with shopping. Safe but lonely.*
That's a good point about being moved from their community. Where my DPs is just 1/2 mile from where they were living so they already knew quite a few people in there. They had also gone to the gym and used the restaurant regularly too.
The fact that they chose to go I think helped too, I don't think it's really something you can decide for someone else, usually by the time it's hot to that stage you might be better looking fir a care home.