I agree with both of you! I enjoy not knowing everything OOC about other characters so I can discover it in play, and I enjoy knowing enough OOC about other characters to make RP happen.
If I’m playing in the Vampire sphere, I find it useful to know who the other vampire characters are, so I know who to look for if I want to talk IC about vampire stuff without a lot of hemming and hawing to make sure we’re not breaking the IC Masquerade by doing so. On the other hand, I don’t want to know what their sheets look like or what their backstories are because I enjoy that mystery.
But I’m also pretty sure everyone draws the line dividing “things they like to know about OOC” from “things they like to not know about OOC” in a different place. OOC Masq is a spectrum.