No what you aren’t getting is that the measurement units are arbitrary. However the divisors for those units is what makes the measurement system useful for people. If you are in construction it’s much more useful to deal with whole numbers then it is to deal with fractions. Hence if you want a third of a foot, you want 4", not .166666 of a Meter. If you are drinking beer you count by the number of glasses of beer whatever size those happen to be, you don’t count in Milliliters of beer. Measurements are supposed to be USEFUL to humans first and foremost, and moving a decimal to convert a unit to a different unit is trivial and can be done regardless of metric or not, and isn’t really useful.