When you are playing a roleplaying game, there are usually a set of rules that you have to follow. Your characters can only use certain weapons, read certain languages, run so fast and carry so much stuff. Usually, when you interact with these rules, you add a random element, rolling dice when you try and perform an action, so sometimes you fail, and sometime you succeed impressively.
Some people, and some games, view these rules as a framework to build from, as only a basis for the play. If it would be ‘cooler’ for something to happen, but the rules forbid it, then you should go with it. The rules are only a guideline. If your hero could really do with having his horse ready and saddled as he leaves, then go for it, even if the player of the hero forgot to even buy a horse.
I am not a fan of this style of gaming. I much prefer to see the rules as an encompassing framework. If your character can only run ten feet a second, then that’s how fast they go. Within the rules, you are free to play as you wish, but the rules define the world. In the real world, you don’t get to fiddle the value of gravity so you can make the leap across the chasm, so you don’t get to fiddle it in the game either.
If you use the rules as an encompassing framework to play within, then you can actually achieve things. If your GM fiddles dice rolls to keep characters alive, then the players can never achieve anything, there is no feeling of winning if you knew that you could never have lost.
You are playing a game, and only cheating yourself if you play fast and loose with rules. It’s generally held that you cannot win a roleplaying game, and that’s certainly true, in the sense of winning a game of chess, or football. You can win a situation, achieve a character’s goals, or excel in a chosen field, but you can only do this by playing within the rules, and not discarding them for something that you think is ‘cool’, but the other players may not.