True, but it was the 18th century. They could measure earthly things well enough, not so much photons.
It’s a bit of a shame it wasn’t redefined as 1/300,000,000th of the distance light travels in a second when it was redefined, but the redefinition was about 50 years too late for that to happen. A difference of 0.07% in the base unit of measurement used by all science would’ve been far too much for 2019, given all the precision measurements we do these days.



Nature doesn’t care about anything. It is not a conscious thing. The size of the Earth, however, is a natural phenomenon, just like the speed of light. It just isn’t a universal constant, relatively unchanging though it may be.
A multiplier is obviously going to be necessary whatever the base measure, because there’s no universal constant that happens to be of a useful, human scale. Or I guess you could use something like the wavelength of the hydrogen line – about 21.1 cm, a fairly useful length – but that isn’t really inherently a special wavelength, it just happens to be useful in radio astronomy.