Comment by mitxela

It's a defense. It's like having a moat around your castle. You don't need a moat to repel invaders since you also have a wall, and you might not get invaded anyway.

There's no law saying you have to do clean room RE. It's legal for me to look at a decompiled driver and write my own driver from scratch. It's not legal for me to just copy the decompilation, and a clean room environment is solid proof that it wasn't copied, but it's not the only way to not copy it, since I could also just not copy it.