Ghosting is hurtful and cruel. It says to the other person, "you don't matter. The years of friendship we've shared don't matter. You are nothing to me." It may even feel like saying, "I never liked you, we were never really friends." It breaks trust and makes you question everything. So as well as being so hurtful, the person who's been ghosted has their memories of the friendship destroyed, too. Not to mention if there are mutual friends or groups involved, the one who's been ghosted is left feeling awkward and uncomfortable about what may have been said and whether she is still welcome in shared spaces.
I get that people dislike confrontation and that it's unkind and pointless to list all of someone's faults to them, especially if you believe they can't or won't change. But if you have actually been good friends at some point, and they haven't done something abusive to you, then I do think it's unfair to drop them without a word.
Just say (text, even! email! probably better not to be an in-person convo), "The friendship isn't working for me anymore. I don't want to keep being in touch. It's nothing you've done - I just feel we're too different now. [Or, if you're going to be honest: I can't get past this thing/situation/change.] Of course I'll be civil and friendly when we see each other at book club/sports club. Take care."
How hard is that? If I got that text, I would respond, "thanks for letting me know how you feel. I'm really sorry if I've done something to hurt you, and if you change your mind and want to talk about it, let me know. Otherwise, I'll wish you well, and see you around." And I wouldn't try to get in touch again.
Of course it would hurt and make me really sad. But at least I'm being given the dignity of knowing what's going on. At least I'm being shown that I matter to that person, and that our friendship meant something. And I'll know how to conduct myself if I bump into her and that there's no drama with mutual friends.