With the right controls it might be a better (more flexible) version of Vim's block selection mode. Which I use almost daily, it's super useful but depends on lines being vertically aligned, which multiple cursors don't need to care about.
But I don't see another purpose for them; find-replace with regex support and macros only fail in rare cases where actual syntax parsing is needed.
But I don't see another purpose for them; find-replace with regex support and macros only fail in rare cases where actual syntax parsing is needed.