That’s just wrong. “Kilo” is ancient Greek for “thousand”. It always meant 1000. Because bytes are grouped on powers of two and because of the pure coincidence that 10^3 (1000) is almost the same size as 2^10 (1024) people colloquially said kilobyte when they meant 1024 bytes, but that was always wrong.
Update: To make it even clearer. Try to think what historical would have happened if instead of binary, most computers would use ternary. Nobody would even think about reusing kilo for 3^6 (=729) or 3^7 (=2187) because they are not even close.
Resuing well established prefixes like kilo was always a stupid idea.