Today, a friend of mine had a few really long wiki pages whose revision histories he wanted to delete (specifically, chapters 1-117 of The Count of Monte Cristo), to save some space in his database. So, he went to do php deleteOldRevisions.php --delete and then, oops, his finger slipped, and he accidentally hit enter when he meant to enter the page IDs. So he lost the old revisions for every page on his wiki. (See https://www.mediawiki.org/wiki/Manual:DeleteOldRevisions.php )
I think back to how, over the past months, he spent countless hours putting a detailed edit comment for almost every single revision, including wry remarks; friendly banter; Twitter-style 140-character social commentary and provocative philosophical musings on the meaning of life and the universe, and whatnot; and now all those are gone. (Now I feel smart for never bothering to enter any edit summaries on that wiki.)
I'm thinking, it's probably best for the script to ask "Are you sure (y/n)?" when the user doesn't put any page IDs.
The script should also probably have a parameter to allow the page titles to be read from a text file, kind of like what deleteBatch.php offers. https://www.mediawiki.org/wiki/Manual:DeleteBatch.php That would probably mitigate the potential for screw-ups.