[ztjio]

It's rare but some source material is created with the assumption of overscan, whether that affects on-screen graphics or even some cases just total garbage is produced into the overscan areas... it all varies, but from the TV maker's perspective, doing what you're describing means this garbage never appears and they never get calls from confused angry customers who think their TV is broken because some broadcaster has some garbage at the edge of the feed.

[account42]

Can you name a single example from this millenium?

Overscan makes abosolutely zero sense since the move to digital formats for transmission and local playback.