In CS GO's petrol, smoke emits from fire. To be removed from ''a'' game would make the particular weapon less realistic. The requester of any hacks that could gain a favorable advantage would be unfair. It is like ''Hey, give me handicap because I am a little worse than you''. Then again, to remove smoke would clear the sight and path, leaving the player with ease of access. But to have smoke, will continue to second guess the player, and to prevent further progression of their worm(s). Which is the petrol's job to do.