Actually, 1/10,000,000 of the distance (as calculated in the late 18th Century) from the Equator to the North Pole on the meridian that passes through Paris.It was coincidence, because meter was chosen to be 1/10000000 of half of Earth meridian. It just so happened that 10 meters of water presses roughly as one atmosphere, "roughly" - not exact. But the approximation is good enough for practical reasons.
I like the hybrid system used in the UK. It has a particularly British eccentric charm. Surely I'm not the only American who gives his answer in stones (14 lbs.) when asked for his weight, or estimates moderate distances in chains and furlongs. That almost nothing useful is communicated is irrelevant. Pragmatism is overrated.
I learned this essentially obsolete system when I lived in Jamaica, which was officially committed to the metric system even back then. Nobody used it, though, certainly not the farmers and fisherman in the coastal village where I lived.