I didn't say it was SI units, but it's easily convertible to them. Metric isn't magic, but it's a cohesive set of legos that can be transformed easily without requiring messy arithmetic and hard to memorise scale constants.

Are you not pretending people use the modern, most-precise definitions in the day-to-day just to give yourself a stab at claiming that Metric is awful? Non-metric would face the same dilemma when trying to establish units in a way that can be scientifically replicated. The counter point is that non-metric is so bad that people don't even bother using it in this endeavor ;)