I honestly thought it was more of a steroid user's problem and that as a natural I didn't have to worry about it.
I wish the relative ridiculousness of this comment would be enough to warrant you not handing advice out on the training board like you've been training for 10 years. It completely destroys your credibility and shows an extreme lack of experience.
As for your original question, most steroid users tend to tear muscles because tendons and ligaments don't grow in size and strength at the same rate muscles do while on AAS. So you have a tendon capable of moving, for example, 225 lbs in a bench press, supporting a muscle that can now move 405 lbs. Something has to give. It's like using an elevator cable rated for 1000 lbs on an elevator rated for 2000.
Naturals tend to tear muscles because of excessive or sloppy range of motion coupled with too much weight. Dumbbell flyes that are either too heavy, too relaxed or too deep would be an example.