Article's point is though that they shoveled useful and relevant problems at them. This is extremely clear if you spend some time reading the BSTJ or the phenomenal "The History Of Engineering and Science in the Bell System" books.

So while there were not significant pressures to produce products there was a culture of working on relevant problems or in areas connected to relevant problems. ... rather than going full open-loop gazing deep into the category theory of their navels -- which appears to be an occasional failure mode of academia.

In working with academics in niche areas there often is a thirst for applications-- like you've found some interesting idea but where to go next? What constraints need to be solved for to make this interesting property into something useful. Applications would be a good guide if anyone would provide some, but the connections often don't exist. Part of the magic sauce of Bell labs must have been this enormous science and engineering driven industrial corporation that could just flood real problems at people who needed them.