This used to be called line lock. For 1/4 milers it was a help to get the engine revved up to the torque band while heating the rubber on the tires to get better traction. When the green light comes on you release the brakes and go.
Sounds like a good way to lose. I can't say I've been to a track for years, not that 1/4 mile was ever that exciting to me. But the burn outs were done in a "bleach pit" The thought being that the bleach would somehow help to soften tires. It was more to create tons of smoke than anything. Once the tires were hot and sticky, you wold go to the starting line. The idea was to have better traction at the launch so you could get more power to the ground. If you were spinning your tires, you weren't applying it to forward momentum.