You haven't been to India, have you? The capitalist push to get every Indian eating addictive junk (most commonly with the use of sugar) is as aggressive as it is anywhere else in the world.
I would blame our monkey brains instead. India has no shortage of traditional sweets that predate capitalism (Indians even knew sugar far before Europeans did), but in the previous crushing poverty that lasted millennia, only a tiny fragment of the Indian population had the opportunity to eat themselves to gout, diabetes, obesity etc. Now, almost every Indian can eat to satiety and beyond, for the first time in history. And the aftereffects show.
Capitalism is fairly efficient at providing people what they want. If our monkey brains crave sugar, sugary treats it will be.
We need to get our monkey brains under control, and not just with regard to sugar. At least some HNers are probably working on digitally addictive products, and then there are the old-fashioned drugs like alcohol and opiates, too.
Why is social media shit? Well, “the platforms are incentivized to demonstrate growth in profit to their investors, so they optimize their system for maximal engagement and retention over time, transferring the same incentive to creators, so many creators who would have made better work before desperately churn out poorly made material about whatever is popular and other, more interesting content is ultimately less common on the platform, with the root cause being the constant need for a growth in surplus in all areas of social production” is a better answer, but “it’s capitalism” is still an alright start.