[underwater]

“Hey, I heard you’re opening a baby store. Did you know John and Mary are expecting? Here’s their phone number, you should call them up.” vs. “Hey, I heard you’re opening a baby store. If I know anyone who is expecting I can let them know.”

[pests]

But really your second example ends with "But when they do come inside you'll know I sent them and you can ask them their name yourself."

Same knowledge as your first example (names, expecting). I do admit you only get the information from people who come into the store.

[underwater]

They’re vastly different. John and Mary can choose exactly who they want to reveal information to.

[jnwatson]

Not on the modern web.

[EGreg]

How so?

[propogandist]

Signals. Searching for specific things, emails you're receiving in Gmail, videos you watch online etc.

Given Target was able to figure out someone was expecting based on behavior in their store, back in 2011 [1], even though they dont have a loyalty program, imagine what can be done with so many trackers that are on the web datamining your behavior from one website to another.

[1] https://mobile.nytimes.com/2012/02/19/magazine/shopping-habi...

[underwater]

The original assertion that advertising and data sharing are equivalent. But even in your examples the information is still fire-walled.

Google can know that you're expecting, because of a congratulation email. Facebook can know you're expecting, because of a life event. Arbitrary companies can't know who their baby store ad is being shown to.

You can argue that Google and Facebook are too big, and data being shared between YouTube, Gmail, Google Adwords, etc. is suboptimal. But that's still better than a company that will freely sell a database of information to be resold, mixed, etc. forevermore.

[EGreg]

But what signals can third party domains get if third party cookies are disabled?

Is fingerprinting so good that cookies are now irrelevant? I mean most mobile devices have the same screen sizes etc.

[ensignro2340]

> emails you're receiving in Gmail

I'm sorry but if you care about privacy, you shouldn't be using Gmail.

[joesb]

Right. "You can ask them their name yourself"

That doesn't mean they are going to give you their name.

And if they choose to give you their name, it's their right and responsibility.