A menu rarely lives in one place any more. There is the version at the till, the one guests see when they scan a QR code, the menu on your website, and often a separate list for an event or a set menu.
Edited separately, they drift. A dish sells out but is still bookable online. A price goes up at the till but not on the website. Guests notice, and staff end up apologising for it.
In ManageHex, the menu, opening times, offers and event pages are managed where your venue already runs, so an update reaches each of those surfaces together rather than being repeated by hand.