I know that and you know that. Personally I had to get the experience by buying a Medium set for my 34" bass before I understood the complexity. And for the random buyer of bass string sets, it shouldn't be necessary to search the internet for a pdf by default, just to get the correct string length for your bass. IMHO, of course.
Besides I think their table is wrong. I challenge everyone to come up with a production bass with 34" neck scale that manage to fit a d'Addario Medium set.
exactly my point about the potential confusion.
Other string manufacturers don't state a string length (at least that I know of), they use more common neck scale.
In the end its really not too complicated because once you know which string length fits your bass, you can just keep buying those. But at $24-27 per set, it would be kind of a PITA to make the wrong decision based on mis-reading scale for string length.