Nope, wrongo.I have been gunsmithing for 35+ years now, and scopes are so much better now than they were even back in the 1980s when I started that I tell people just the opposite. Forget about iron sights, spend that extra money on a good scope and don't even worry about it. Good quality scope failure is so rare now that even so-so brands offer a lifetime warranty because they know they will rarely if ever have to honor it.
Scopes fail in the field every year. Iron-sights, properly zeroed, are cheap insurance to save the hunt.
No hunter ever stopped their hunt to call up Leupold (or whoever) for immediate warranty service on their optic because it fogged-up, failed, or broke after Bubba dropped his rifle from the tree stand. They either revert to the iron-sights or go to a second rifle.