In Emacs, there's an mc-hide-unmatched-lines command that temporarily hides the lines between the ones with cursors. This makes multiple cursors usable with up to a screen-height number of items (being able to place cursors by searching for a regexp helps).
I agree, though - MCs are most useful for simple, localized edits. They're nice because they don't require you to mentally switch between interactive and batch editing modes, while still giving you some of the batch mode benefits. For larger or more complex edits, a batch-mode tool ("Search and replace", editable occur-mode in Emacs, or even shelling out to sed) is often a better choice.
That's why the Ki editor has a feature called Reveal Cursors (https://ki-editor.org/docs/normal-mode/space-menu#-cursor-re...), which is specifically made to solve this issue
Which is still a net positive over the alternative?