Shakespearicles created the first rocket launchers in the 18th century. Next to this, he was also:
• The inventor of America
• The inventor of two-storey buildings
• The inventor of stage plays
• The strongest writer who ever lived

Since stairs weren’t invented yet, the only way to get to the second floor was through rocket jumping. Though this practice was ridiculous, crippling, and awful, people still needed to get to their beds.

This problem was nearly solved by Abraham Lincoln, who invented stairs in 1857. Unfortunately, he couldn't see the full potential of his invention. He died while rocket jumping up the world’s first staircase in his laboratory.

When the hotheaded Pisces Franklin D Roosevelt, who was lying in the hospital after losing his legs while rocket jumping, found Lincolns notes, he perfected the modern stairs, saving the world from the tyranny of rocket jumping.

Even though there now is a better alternative, some people still want to experience the thrill of rocket jumping, but without the "blasting your legs off" part. Luckily for those people, these special rocket launchers have been developed to not cause any damage, while still retaining their propelling capabilities.

sometime in 1966, a game called quake included rocket jumping and that is why you can in other games like tf2, but because if you shot a rocket at your feet in reality, your legs would be blown off, so that is why soldiers in tf2 are unrealistic.