Copying unequal measures
How do you cut/paste a multiple-measure section of score whose measures are not equal? If you "add new measures" and copy and paste, chaos ensues. You can do that, and find the start of the damage and attempt to fix it measure-by-measure note-by-note, but one might hope that there would be a better way.
While I employ subtly unequal measures for my hidden rests (because there is no "non-counting pause" feature), music whose measures are unequal is not only common today, but was common 400 years ago (or at least the way we represent amensural music today).