Bronze : Why you're there and why you stay there.

In bronze, most players are not all that good. They're not that sophisticated. Obviously, we'd all be ranked higher if we could.

In bronze, most people don't bait well. In fact, since it requires communication, it happens so infrequently as to be negligible in most matches. This means aggression will generally win games. Yet, because the "pros" don't play generally play aggressive early, because both teams can and do bait, new people who want to get better THINK they're supposed to play passive.

Every time you run away, you give them free damage. Every time you don't follow up and get the kill, you likely get one of your teammates killed instead. When you give up because you're down four kills, and play passive to protect your kdr, you end up bleeding out slowly and still lose.

If you have a strongly negative record (100-135, 220-265, 300-380, etc) and your kdr is generally positive, you are playing to protect the kdr, not win the game. Kdr gets you mastery points on your champion. Team objectives win you the game. Aggression in bronze generally gets you objectives.

This isn't true in, say, diamond, where you have to actually communicate hard to set up plays, and baits happen regularly. If you're playing passive in bronze, all you're doing is letting your opponents gain an advantage