There are reasons for why that is possible, for better or worse.
To reverse malicious actions that may have been taken by other people that got access to the account for any reason for example.
There may even be legal reasons for why that is the case. Licensing law can be quite complicated.
And then there is the fact that if it’s hidden it’s effectively gone anyways and that may actually be what people actually care about. Not whether or not they technically still have that game or not. People wanting a clean library is a thing and it ties into the concept that is the right to be forgotten.
Yet… Ubisoft did go and “remove” the keys for the crew when they shut that one down. No one but them can really say if they actually deleted them or not. though I have my doubts with how that company has acted in recent years.