Rene Lamontagne wrote:

Why in hell do we need that?

Marketing Departments, and proper standardization of magnitude prefixes.

Using a power of 2, HDDs would look smaller than using a power of 10.
Marketing could make HDDs look larger to computer illiterates by
describing capacity in, say, megabytes.

2 ^ 20 = â€*1,048,576‬ mebibyte (megabyte misnamed, renamed with new prefix)
10 ^ 6 = 1,000,000 megabyte (properly named)

1.05 megabytes = 1 mebibytes

Back then, and with HDDs being much smaller, any incremental increase in
size at the same price meant more revenue from customers that thought
the same-priced drive gave them a wee bit more capacity.

kilo, mega, giga, tera, and so on were defined as powers of 10, not 2.
Only until computers showed up which work in binary did those prefixes
get misused to represent magnitude. A megabyte should've been 10 ^ 6,
but was first defined as 2 ^ 20; i.e., the mega prefix got misused.
Back then, there were no magnitude prefixes for binary values.

If you are old enough, you would've been around when the naming
correction happened. mega is a decimal magnitude. mebi is a binary
magnitude.