Format whole drive vs. partition

[Michael Hipp]

I've been doing this for a while when I intended to use an entire drive 
for one FS. I figure it reclaims a few bytes.

   mkfs -t ext4  /dev/sda

Instead of:

   mkfs -t ext4  /dev/sda1

Then I read an article that said you shouldn't do that, but no 
explanation why not. Any thoughts?

Thanks,
Michael