The trouble with pdf isn't so much lack of open source tools, rather that it's a horrible standard to begin with. It's basically unparseable. It's the file format of choice if you want to distribute content to be viewed but not analyzed. I can only assume that's by design.
Authored Comments
Also from the pedagogical realms, and even more obscure than Logo, was PILOT. I (largely) wrote the Wikipedia article about it.
https://en.wikipedia.org/wiki/PILOT
The trouble with pdf isn't so much lack of open source tools, rather that it's a horrible standard to begin with. It's basically unparseable. It's the file format of choice if you want to distribute content to be viewed but not analyzed. I can only assume that's by design.