Confluence keeps each and every saved version. The size of the database grows uncontrollably that way. In the administration it must be possible to indicate how many versions of the changed page Confluence should keep.
For my project, as an example, 3 recent versions (or 5 at max) is more than sufficient.
I don't need change of each and every character to be saved as a version. It eats up database space and system, also, becomes slower.