I know this post is from some time ago but I came across it when I couldn't work out why some of my activities weren't being exported. I had to scroll my way through several years of activities before I was able to export everything. As @radii398 said the default should be export all.
Yes, activities' list is loaded partially and CSV prints only those loaded, but sure it would be better to make it real export of all or by selected dates.
For now you can export everything as FIT files at garmin.com -> Profile -> Manage Data -> Export. But then you would need something to convert those to needed format. Or look for scripts for printing in other threads.