I think they find it acceptable because, well, people seem to be accepting it. The majority doesn't seem to be interested in deleting any accounts but simply abandon them. I do wonder why Microsoft/Skype prefers accounts not be deleted, though? Message history perhaps? When designing databases, this is a matter that's important: do you delete objects or do you flag them deleted to prevent holes in the related data? Obviously I've no idea if that's what is going on at all, but who knows. :)