While it would he handy to have everything integrated, it's not always vital. We don't need to convert kilograms to seconds very often. Artificially enforced systems have always had trouble replacing older anachronistic ones that are otherwise still useful. Ask people in the UK about their cars' efficiency and you'll often get an answer in miles per gallon.
There's nothing magical about 10, either, other than the accidents of evolution that left us with ten fingers. Base 12 is also extremely convenient, and comes from Sumerians counting with their thumb against each of the three joints on 4 fingers. Go through that process once for each finger on the other hand, and you get 60. And of course, in any industry where things are packed into packages, like nearly everything we buy, dozens fit better than tens. 60 divides very neatly into many convenient and geometrically simple fractions, and a lot of what we do with circles benefits from this.
We probably would have been better standardizing on a base unit that's a power of two, which has more mathematical weight than ten does.
The problem is, the reasoning you are using is how false equivalency gives itself credibility that it cannot earn on its own merits. It's not an opinion if I say an apple is not an orange, and these two events are not the same thing. Opinion is not part of this argument. This is why people argue endlessly about politics-reality has been divorced, and it's just opinions. This serves absolutely no purpose.