I think all MMOs should give you the option to completely remove a player from your game if you wish to and it should be for their whole account, not just that one character. Putting someone on your blacklist should give you the options to make them disappear for you, make yourself disappear for them, exclude each other from any and all matchmaking/party finder listings and make it so they cannot find you using the Player Search function. These options would also include being unable to enter your regular and FC houses (assuming you are the FC leader and owner of said house of course).
It would help with more than just stalking but also with many other situations. For example if you've had a falling out with a friend or a partner of some sort. Some people struggle with moving on if they have to keep seeing that person in-game constantly and they often change servers or quit the game altogether because of that one situation. It would tremendously help many people feel much safer with continuing to play the game after any such incident. Maybe the only single exception should be PvP so that players who are really good don't just get blacklisted by everyone and never get to actually play PvP.
The reason for this is that even if you block chat communication, they can still see you, harass you in-game with their character, use emotes, follow you around and so on. Or if you are a more sensitive person and you need to just not see that player anymore, you can completely remove them from your game and yourself from theirs. I cannot currently think of any real downsides to this in regards to game functionality but I'm sure any that come up can be remedied fairly easily by adjusting some of it.
On a related note, if you remove someone from your friends list, it should remove you from theirs as well. This will prevent a whole lot of stalking that goes on in this game and it seems like this is one of the very few games that are still so behind in its friends list system design.