You can explain this problem drawing a comparison with a library. There are many books. Small one and big one, thin and thick ones - everybody can imagine that. Now if you want to store more information somewhere it would be rather simpler to add some new pages to a book than enlarge some single pages - if there are several pages of a book larger than the others, this not very robust and how would one find this information if it has no entry in the index of contens?
Maybe it is better to store the new additional information in a further book, a new one with a particular structur.
Imagine how one may get a information if the whole contens of a library would be written in one big thick book? Nobody else could find anything until you find what you want and set the book back at its place...if you are able to carry this enormous book.
Why retrieving the whole Livestory if you only want to know the birthdate of a person?
The mentioned people don't have to understand the architecture of a database but they should trust you. And you organize it so that they can throw their information in this big hole of database and get it back when ever they want it - fast and reliable.