Hm. I would rather divide 210 mm by 7 than 8.3 inches by 7.
…Electrical engineer of 32 years.
Traditional units and subunits are selected to have lots of divisors. That's why the Babylonians chose base 60. You can always cherry pick cases where metric is better. But metric units are only easily divisible by 10, 5, and 2. That comes in handy when you are using a table of common logarithms, which scientists and engineers did in the eighteenth century when metric units were devised. Nowadays we use calculators or spreadsheets, so that really isn't a concern.