Well in a large sense most people in this thread have probably given out enough information to be personally identified. It's not just the younger generation.

To use you as an example it's not that hard to infer that sandra_nz is Sandra, New Zealand, though you give the additional information that you've moved to the UK recently, which explains why your posts are focused around 13:00 GMT. That combined with your posts in /r/sharepoint, and the fact that you talk extensively about the ketogenic diet makes you incredibly easy to identify. Your father has suffered a dramatic brain injury. You're an approximately 40 year old female, 165 cm tall and weigh 99.8kg giving you a bmi of 36.7 (not that bmi is a very good unit of measurment) . You have a cat named mitzy.

I'm trying not to share any real personal information, like your full name, place of business, or address. I'm just trying to show that it wouldn't be that hard to get there. I work in bioinformatics, collecting and assembling tiny pieces of information into a larger picture is what I do, though usually with proteins and genetic sequences instead of personal information. No matter how little people think they are saying online, it can almost certainly be assembled into a full picture of someones life with just a little bit of effort. Especially if you're a government agency which can always link any piece of information to an IP address. You're right, privacy online is really just an illusion, anyone with even crude tools will be able to find identifying information about you, thankfully they tend to use it for advertising more than anything else.