This is going on precisely because the law has not been well written.
"Until the ball is in play all opponents must remain: at least 9.15 m (10 yds) from the ball, unless they are on their own goal line between the goalposts". So any player who's 10 yards away and moves closer commits an offence. It doesn't say so, but for me that means any attempt by an opponent who's less than 10 yards away to go closer to the ball is an offence. The only reason players do it is because it's not penalised.
THEN you can look at the other bits.
"If, when a free kick is taken, an opponent is closer to the ball than the required distance, the kick is retaken unless the advantage can be applied; but if a player takes a free kick quickly and an opponent who is less than 9.15 m (10 yds) from the ball intercepts it, the referee allows play to continue. However, an opponent who deliberately prevents a free kick being taken quickly must be cautioned for delaying the restart of play."
It's no good arguing it's "semantics" when the law is self-contradictory. The first bit says it's a retake unless there's advantage (to the team with the kick, you'd hope that means). The second bit introduces the idea of a quick free kick (without defining it - presumably without waiting for the referee's signal) and says you don't retake it even when there's no advantage, and we have to argue what "intercept" may mean. Then it talks about "deliberately preventing" a quick free kick, which leads to nonsense like how do you prevent a player taking the kick (the ball moves) unless the opponent is actually touching the ball.
I might be missing something but, for a "ceremonial" - on the whistle - where does it say to caution a player who encroaches (e.g. from a wall) and intercepts the ball? He hasn't prevented the kick, slowly or quickly.