The reason you think you are getting decent latency without this trick is because of lag compensation.
Lag compensation is good in the sense that it you don't have to lead your shots as a sniper to get a head shot, BUT, there's the very serious problem that each player is literally playing the game in different points in time in comparison to the host.
That's how you end up with those strange situations where you get headshotted after you broke line of sight with a sniper.
Lag compensation is ideal in sub 80ms environments. It gets rid of that slight delay so you don't have to lead your shots a tiny bit when someone is running, but when people are at 100ms+, you get some very retarded results that wouldn't fly in a competitive match.
Basically your being deceived into thinking your not lagging, you are.