As a moderator of a campaign, I find that I'd like to flag ALL ideas that are similar, but not necessarily all to each other. When I access the Merge Ideas "cart" my only option is to merge all of these ideas to one parent idea, or to remove them from the cart.
So instead I must locate only the ideas that are similar to each other, put those in the Merge cart and merge those ideas, then move on to the next. If I encounter a third, I need to relocate the one I just merged and repeat the process. It would be easier to go through all the ideas and locate any possible duplicates to review.
Often our idea review before merging is done by more than one individual, having more Merge Cart options is desirable.