An standard ATX motherboard is 305x244mm, and cases don't normally list that spec. I see Corsairs site does.
They usually list max cooler height, GPU length and PSU length. Exactly why that's listed, I have no idea.
272mm isn't even a dimention of any motherboard form factor as far as I know.
mITX = 170mm x 170mm
mATX = 244mm x 244mm
ATX = 305mm x 244mm
EATX = 305mm x 330mm
There are non-standard variants, but they're hard to come by these days, if they're even still produced (BTX, DTX etc)