The conspiracy theory exists due to quirks of human attention and the wider metadata economy though.

You mention something so you're thinking about it, you're thinking about it probably because you've seen it lately (or it's in the group of things local events are making you think about), and then later you notice an ad for that thing and because you were thinking about it actually notice the ad.

It works with anything in any media form. Like I've had it where I hear a new thing and suddenly it turns up in a book I'm reading as well. Of course people discount that because they don't suspect books of being intelligent agents.