> but up until recently it felt like only Google or Facebook had access to analysis capabilities strong enough to draw meaningful conclusions from disparate data points
Every advertiser can access data like this easily, when you click "yeah sure" on every cookie banner this is the sort of data you're handing over... you could buy it too.
Every time someone says "they're listening to your conversations" we need to point out that with a surprisingly small amount of metadata across a large number of people, they can make inferred behavioral predictions that are good enough that they don't need to listen (it's still much more expensive to do so)
On a macro level people are very predictable, and we should be more reluctant about freely giving away the data that makes this so... because it's mostly being using against us.