"Having those kinds of (vulnerable) conversations gets you clued into what kind of a person this is: Is this a person who is in touch with themselves, who can have a real conversation, who can be present with me as I'm sharing something that's vulnerable?"
Having real, semi-vulnerable conversations early on in getting to know someone (before having the herpes talk) can clue you in on who it is you are connecting with. This can be a great litmus test as to whether you feel like you can trust them with your deeper vulnerability. Ultimately how they handle receiving your vulnerability in smaller doses early on is great data! This will help you determine whether you want to go deeper by disclosing and everything that comes after.