For all the many times I have used defrag it has been very good maintance and good for the files it is very good to have back up files for the reason you may lose files but for the best part I have had no trouble in defragging my harddrive(s).If you had a problem it pretty well means tha t your hard drive was on it is way out .
Sounds like an old wives tale about wearing out hard drive. Don't be naive! Defrag as often as needed!!!