The reason for 16EB is because the subtraction of 47-2048 results in a negative number. Apparently a bug that has already been fixed.
The reason is performance. Have heard of hard drives with 4k sectors? They had to be 4k aligned in order to have the correct performance. Other device and manufacturers have discovered there devices didn't get the full performance without different alignments.
A decision was made as a catch-all that 2048 would eliminate most if not all of the performance reducing alignments. Given how cheap storage is no one will miss the loss of 1MB of hard drive.
Originally, a 63 sector gap was left and it was used to fit drive overlays for bios that didn't support the full size of the hard drive. Especially common when computers first got 1-8gb hard drives. However, hard drives now use LBA and the drive overlay non-sense is a thing of the distance past.
Although now we have to switch to GPT with hard drives bigger than approx 2TB since MBR doesn't support that.
fdisk. In version 2.32.1 I can no longer enter starting sectors below 2048.