The outward force of the air pressure will mash a fresh patch tightly against the tire ply or rim, making the patch more secure as pressure is applied to a new patch for months, compared to the 20 seconds of your thumbs.

I patch tubes when it's faster to do that than getting a new one from a local supplier. Speed is of essence as I flip/retail about 100 bikes every season.

When I have time to kill, I go work on the next bike to sell, not waste it on punctured tubes I regularly toss out when the pile gets too big.