Applying a swap on two sets is different from applying a swap twice on the same set.
Maybe I misnamed the help by calling it a hint? Let me be clear - the idea is that with puzzle games the risk is higher than other types of games that the player gets stuck and abandons the game.
When a player gets stuck which outcome do you prefer - that the player decides on their own to see the solution and continue OR that they abandon the game?
When the player pays for a game and gets stuck they are likely to search for the solution online - that is outside of your control. And if the player is playing some game for free they are even more likely to just drop it and do something else.
In action games this issue is called difficuly spike - if a section of the game is a lot more difficult than the previous this causes frustration and possibly rage quit. Designers avoid that.