Yes, nobody likes when info is leaked. but keep in mind info is ONLY leaked because the source itself is withholding information.
Now... I have no idea why A&F and other mods will occasionally post details of yet-to-be-released event ahead of time and then sometimes they don't. But I've learned to never question the inner work of Gree.
P.S. if it's against ToS to post unreleased event info, shouldn't A&F be the first to be banned?