Little quirks- most of us in the US learned the SI system in school, only to find that in the real world, "metric" does not mean "SI". So, for example, I find everyone talking about pressures in bars, and that never even came up when we were doing "metric" stuff. And then I see mill test reports, and they'll show yield strength in kgf/cm^2. Logically, the standard of volume would be cube of the standard of length, but it's not- it's off by 1,000. Logically, the base unit of mass would be the mass of water in a cubic unit- but it's off by 1,000,000. Or the mass of water in a standard volume, but that's off by 1,000.
Arbitrarily choosing the standard of length as 1/10,000,000th of the distance from equator to pole unfortunately does not simplify much in the way of calculation. Setting the units so that a unit mass weighed a unit force, and consisted of a unit cube of water would have been a much better start to it all.
If you'll take that original problem, and look at the metric equivalents, you don't really solve anything. If you need to add meters and fractions of meters, you have exactly the same problem you do in feet, and wind up just converting everything to decimals and adding. On the few metric engineering drawings I've seen, they handled this issue by just showing every dimension in millimeters, regardless of how big it was, which is not an overly convenient system, either. In that case, the original problem becomes 5613+610+2184+1676, which is not too convenient for adding in ones head.