I'm guessing the comments were meant as encouragement as they probably thought you could keep running, most folk who do 5k in 30ish mins will run all the way. I'd suggest just slow down a little bit and it will be easy. If you are in reasonable shape, 25mins should be doable fairly easily.
The banning of performance enhancing drugs is less to do with cheating as it is to do with protecting the health of the athletes. It eventually becomes a game of who is most prepared to push themselves towards risk of death or disability. All competitive sport is about achieving an advantage, e.g. the superfast swimsuits, better training, better food, etc that your opponents do not have.
Once a ban is in place, of course it is cheating to use them and appropriate penalties should be in place for those who flout it.
The Furman FIRST plan works, 3 hard running sessions a week + three cross training sessions. It is not the easy option though, as except for the rest day you are working hard every session. Works if you are time poor or injure if running too much.