alt Hacker NewsBlackboard is definitely a really strong contender for the worst software I've ever had to use. When I was in uni, I went so far as to write an alternative that scraped the content from blackboard and published it on a site that I could actually browse sensibly.
They were paying exorbitant amounts of money for the license too.
Applications like Blackboard exist because of the genre of "Checkboxware."
A University must comply with Laws and Regulations X, Y, Z, P, D and Q and a host of other regulations the University never heard of and Blackboard went through the process to "comply" with those checkboxes. So, if you deploy Blackboard, you tick all the checkboxes automatically.
The fact that Blackboard was a garbage content management system and a terrible grade recording system was irrelevant--because the "better" systems wouldn't check the boxes.
(I say this as someone who, as a lecturer, had to manage the account logins, mailing list, and Subversion source control system for an entire class. I only ever put grades that needed to be "secure" into Blackboard. I did all that because I HATED Blackboard that badly, but it was a LOT of work. And I probably wouldn't have passed any significant security audit; although my accessibility ratings should have been excellent since everything was plain text and plain HTML)