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.

In vscode if my cursor is in a word, i Ctrl+D to select that, then Ctrl+D to select further matches, then begin typing over them. There's other modes too where you can just add more cursors to a line below/above but i find less use for that.

But in vim it's not much slower to do:

    /<search term>
    cgn  " change this this i just matched
    .    " find next occurance AND execute the change here too, i don't have to say "n ." because i used cgn above instead of something like cw

But i still end up relying on

    qq  " stick a macro in q register
    <complex edit sequence>
    @q / @@

For more gnarly stuff

It is more like interactive editor macros where you can see the intermediate results on the fly.

The advantage over search-and-replace is that you get to work with a nice, familiar language (the interactive commands you send to your editor) rather than using regex.