"There would usually be routes"

ah; I believe you are mentally imagining a kids' room floor full of Lego, and adult inexplicable inability to avoid them :)

For me at least, that's not the threat vector.

It's when you go to your office or living room, a seemingly safe place at a safe time and your mind is not running "Obstacle avoidance program", and unexpectedly there's a single sharp piece of lego hidden in the patterns of the carpet or underneath your office work chair, or even when it's in the middle of the bathroom floor in the pitch dark at 3am when you're running to the toilet --> let me tell you, THAT one REALLY hurts, and usually results in secondary or even tertiary damage :P