You certainly can make memory books online yourself and there are several different companies that offer this. However, these can be more time-consuming than you expect to plan and layout. In addition, most of these books are designed for photos and don't allow much room for text. 

With a Beyond the Trees book you get access to our ideas for the content of your book, gained from creating dozens of similar books. And we do most of the work for you leaving you free to make more memories.