HudPainter - Use cases?

Had a discussion on Discord about HudPainter and it's use cases - the documentation kind of just leaves me with more questions than answers.

https://sbox.game/dev/doc/systems/ui/painting-a-hud/

What exactly is the use case for this?

When it says more efficient, is that in terms of performance? Or more efficient in the time/effort it takes to do, whatever HudPainter is designed to do? 

Why would/should HudPainter be used instead of a screen panel + Razor component combo? What can we do with this that we couldn't or shouldn't do in Razor?

If you are making a crosshair it's simpler and quicker in terms of code and performance to draw 4 lines instead of clumsily laying out 4 panels in UI

You wouldn't make a game on the web out of divs and css

Okay thanks, by the sounds of it, it's a pretty limited/unique use case for things like crosshairs then. 

Under the good the HudPainter is a CommandList, so it's a real clean, easy way to draw to the HUD. It's simple stuff at the minute but our intention is to expand it over time, so it's really powerful and simple.