Layout check. Layout as a background image. Usable?

Question

HTML

Hello.
I often come across opinions on the toaster that the layout check for compliance is done using the site layout as a background image.
Please share your opinion, I want to draw some conclusions ..
I've been typing for about half a year. But I have never tried this approach. To me this sounds crazy.
I wanted to know how correct this approach is?
How often do you use this trick, do you use it at all?
To all who responded, thank you.

Answer 1

Used.
A useful thing when a cool designer and high demands on the quality of the product. No need to constantly check and measure every gap.
But if you are doing a regular project for 50k rubles, then do it almost "by eye".

Answer 2

This is most likely done to check the pixel-to-pixel layout, which is not very relevant in the modern world.