See also: timestamps when HN comments are posted.

This is much more interesting because pretty much everyone only participates in discussions when posts are on the front page - it would be tough to schedule/delay a post and stay relevant. Also, the lock-in after 1 hour (or a reply) preventing deletion is huge.

Some HN participants are now kind of "whales" in the startup community - at the very least, this info could be used to schedule cold-pitch emails! (And this is across the entire archive of past users, not just current users. These habits need not necessarily change much.)

Timestamp metadata is all over the place - GitHub activity graph, blog post comments, etc. -- merging timestamps for the same person across their accounts on all the different services offers amazing insights.

The only way to "disable" this is to schedule things or provide garbage data (only when user input is given precedence - like with this tool: https://www.laurencegellert.com/software/github-graph-builde...).

Reason #32* to avoid the application.

* Entirely made up number.

If you're in a group chat, anyone that is in the same chats can see all your messages in there.

That's the one and simple trick.

Correct, but this doesn't appear to be group chat. This appears to be individual chat and the timing attacks based on their online presence. Group chat, by default, is going to seriously hinder one's ability to remain private.