My guess, based on just how horribly censored and astroturfed their subs have become over the last 5 years, is that the targeting of banner ads and stealing personal data for "analytics and sharing with data partners" is not their business model. Instead, they're paid big money to push narratives to the masses of 16-30 year olds that flock to the site religiously.
The group-think on Reddit is far greater than any other site I've ever seen on the internet, including very partisan forums and "media" outlets. And even the tiniest bit of disagreement from accepted narratives - e.g. small subs that wouldn't have even been noticed ten years ago - are crushed and removed without mercy.
What's more insidious is that it isn't just the typical corporate "sponsors" who are pushing sneakers or phones or mobile games. I'd imagine it's deep-pocketed NGOs, state controlled PR and propaganda agencies, and worse.