There's no way I've ever heard of to "destroy all the data files".
You can't "destroy" your files; the best you can do is overwrite them with zeros once or more, as you did, but I'm pretty sure that initializing a drive doesn't do that. It's a pretty quick process as I recall...more along the lines of, if not precisely, a simple erase.
Maybe yes, maybe no. As far as I'm concerned, I "nuked" the hard drive sufficient to my purposes (especially given lack of concern for the sensitivity of the data thereon).
Perhaps someone more
au courant on the subject (such as tacit or joemikeb) could chime in here.
