Not entirely true... depends on paper used, many hardbacks have acid-free paper and will last equally well and are rated as at least 100+years without any deterioration...
Originally Posted by Poppaea
The HC sold today will have a shelf life of approximately 20 - 30 years due to inferior paper qualities. I have books from 1908 - 1958 that look brand new. The paper as white as it was back than. Have a look at the books on your shelf. I bet there are books you bought 10 years ago whose pages are already yellowing.