On the other hand it’s a great signal that whoever uses that is an obnoxious twat and should be plonked.

Pretty sure Fifth Star Labs’ Sky Guide iOS icon does this. Not the whole icon, just the stars in it. Hiding the app in a folder helps but I’m looking for a better alternative just because of this.

The <blink> tag's spiritual successor.

We found that user engagement was substantially increased by making the home page just rapidly flicker between red and green. Some users stared at it for hours!

I mean, use it responsibly. Of course people won't, it's the internet, but a skilled designer may use it to highlight a word or an accent to draw your eye. It can be tricky in dense interfaces to draw focus to something (little tooltips or big buttons aren't the best answers). This is just another tool in the toolbox.