The only reason to have “per cent” (%) as a concept is because decimal fractions weren’t invented yet when per cent was first used; until the past few centuries

The only reason to have “per cent” (%) as a concept is because decimal fractions weren’t invented yet when per cent was first used; until the past few centuries arithmetic was almost exclusively done in terms of integers or ratios (or various mixed units depending on the material being measured). Using 1/100 as a generic unit was a work-around to make numbers less than one easier to compare and recognize by turning them into 2-digit whole numbers instead of needing to do a careful computation to judge between say 5/13 vs. 3/8. There’s not really any particular advantage to saying 0.005 of the amount (or 1 – 0.995 of the amount) vs. 200 times less. Personally I find it significantly less clear (though not really any more or less “impressive”), because doing mental decimal arithmetic takes some extra effort and leaves more room for confusion. That is, it is easier to reason about multiplying or dividing some quantity by 200 vs. multiplying or dividing by (1 – 0.995). But the two numbers are reciprocals; this is grade-school rational arithmetic, not some kind of trick.