I wish everyone would use em
so I can resize the page font size
to match my display adapter, monitor resolution and weak eyes.
it takes very little thinking to code so the text can flow and wrap.
On my computer at 1024 x 768 I have seen pages that have fixed point sizes that are so small I can't see the words without squinting.
If the creator was on 800x600 it may have looked good.
You may have seen pages created by someone with 1600x1200
and their text was way too big.
So please use em and let the visitor choose the size.