stem scraping/pinching? is it good?

A long time ago I read an article about scraping your main stem to damage it and it would repair and come back thicker and stronger and make your buds bigger and or stronger potency does anybody practice this and Is it true?

I think you are talking about supercropping though I will let somebody else with more experience explain it for you. Otherwise you can google it up. Cheers!

Supercropping is essentially bending your plants stems to the point that you break down the cell walls and cause a bit of damage.
As a result, the plant will begin to focus growth to the tops of the supercropped branches, while simultaneously forming a very woody knuckle at the point of the break.
The main applications for this, in my personal experience, is as a method of stress training, letting you essentially bend the plant sideways so your side branches develop as tops. Or it can be used to expose lower branches to more light and to shape the plant in a more productive manner.

I have not tried scraping the plant, and I would not advise doing that.