I think the article is referring to the fact that out-of-band key verification is optional and isn't something that most users will perform. If you're doing out

I think the article is referring to the fact that out-of-band key verification is optional and isn't something that most users will perform. If you're doing out-of-band key verification with all your contacts, and have enabled the setting that'll make WhatsApp notify you about key changes of your contacts, this doesn't concern you.