People are consuming more overall. That's the main reason for obesity. Sugary drinks were common in the past, decades back, and they were very sweet. White bread with jam was a typical school lunch. Yet much less obesity. Ready made packaged meals might be loaded with sugar and the sugar levels might even be increasing, but
Then there is the whole anti-seed oil cult. Like being anti-grain it seems to have been initiated by the paleo diet cult. Maybe some science will eventually come along to vindicate it, but so far it just another dietary fad that makes some people a lot of money.