I've heard this lots of times, and it's complete rubbish.
My boys have always had a severely restricted intake of sweets/chocs. (e.g. under 4 I would buy them 5p of penny sweets about once every 2 or 3 weeks, remove most of the contents of bulky party bags, that sort of thing ...)
They are by now 7 and 9 and occasionally have sweets/chocs. Sometimes they get given a 'big heap', and almost invariably they eat just a few, then decide to 'save' the rest for later and put them on the side (in full view) ... and forget about them! I've lost count of the number of times I have chucked away (or eaten!) bowls/packets of sweets that are languishing on a shelf in the breakfast room.
So they're hardly obsessed with sweets, are they?