I was thinking the same thing but I tend to create a large compressed backup file and upload that instead. My backup file is currently under 100 gigs, the most critical files not my whole system's files. If I backed up my gaming account (I don't need to since I use Steam Cloud) and compressed it, it'd probably only be another 50 to 100 gigs. This way I should never hit the 5 million file limit.

Having said that, I feel 5 million files is too low for a lot of people.