The standard across almost all services is to retain easy-to-retain data when someone leaves. It's just good business: you WANT them to come back.

The only example I can think of are the TV services: Netflix will erase your watched show list if you unsubscribe. But they are very purposefully doing it out of spite: they want to push you towards not unsubscribing at all (so they penalize it even at the cost of discouraging you from coming back ... because they know "subscription hopping" is a thing, and expect you'll come back anyway).

It's 100% a dick move when the TV services do it, but at least it (kind of) makes business sense for them to do it. For Claude it's just alienating their customers needlessly.