[hnmcs]

> I don't understand what people mean when they use it today

By now, it often is used to be friendly. There's a subconscious acknowledgement that long words take people's time. The speaker can even be talking about his own work and tell everyone "tldr version: " at the top.

Google uses it a lot in their own docs: https://developers.google.com/s/results/?q=tldr

You can also choose to pronounce it "teal deer" and use images of a green deer animal to signify the same.

...

In some situations, if you want, you can say it to be mean.