The Idea Wasn't New. The Word Was.
Meat wrapped or layered in bread is ancient — cultures across the world had versions of it long before the 1760s. What Montagu actually contributed wasn't the food; it was giving fashionable London society a single, catchy word for 'food you can eat without cutlery, without stopping what you're doing.'
That's the real mechanism behind why this stuck as an eponym and so many similar foods across history didn't: it wasn't the dish that was novel, it was that a titled, socially visible person made eating it in public seem elegant rather than crude, and the newly London-fashionable crowd needed something to call it.

