Theoretically the names and the very memories of evil people (rasha'im) should be obliterated. Is this aim seriously pursued?
For example, saying ימח שמו after a name doesn't really help obliterate that name. Using nicknames (such as ישו) does help obliterate the name but not the memory of the rasha (to obliterate the memory, one wouldn't talk about him at all).
Also, in the modern world, information spreads so quickly that it doesn't seem feasible to obliterate someone's name.