Because we solve practical problems, and do not nit pick of what is technically correct. We are not drones and easily understand that in this context it's megabytes.
Just look at all that "technically it's mebibytes bla bla bla" in replies. No one cares. Write some code. Or better - go outside.
Just look at all that "technically it's mebibytes bla bla bla" in replies. No one cares. Write some code. Or better - go outside.