TeX does do a good job, but it is not totally unique in this, and it’s not perfect because it doesn’t know enough about glyph shapes to avoid creating rivers.

TeX does do a good job, but it is not totally unique in this, and it’s not perfect because it doesn’t know enough about glyph shapes to avoid creating rivers. The thing that TeX, InDesign, and other systems that can do really good layout often allow is hints for ways to fix otherwise difficult cases (where it might be good to hyphenate or introduce a line break). Word is in a tricky middle ground where it is ostensibly concerned with the pure content of the document (where you shouldn’t be worrying about line justification issues) but is being used to produce final output where you would expect to be providing those fix ups.