Someone linked me
this sca offsite. And I still see no proof that world or dimensions meaning universe. World doesn't always mean universe; it sometimes does, but it also has been used to mean planet. Such as Emerl, Perfect Chaos, or Dark Gaia destroying the world simply meant planet. Dimension and planet have also been used in different sentences.
And there's only proof that the Dream World in it's entirety is 4-Dimensional or Universe in size, not the individual dreams. The individual dreams are simply pocket realities of unknown size. So in other words, Zamasu and Cal are the people being most reasonable here.