Much of the discussion of any proposal to define “broadband” tends to center on download and upload throughput. Download and upload throughput are important, but neither is precise or diverse enough to describe broadband satisfactorily.
Indeed. The issue isn't broadband itself, but the poor state of the U.S. telecommunications infrastructure that has tended to keep the focus on speed and latency, largely because it's so lousy in much of the nation that its ability to deliver what could even be charitably described as broadband is sketchy and often nonexistent.
Broadband should be instead be defined as fiber infrastructure to the premises. As the FCC notice suggests, any definition based what the pipes can carry rather than the pipes themselves will devolve the discussion into a "how many angels can dance on the head of a pin?" debate and result in the the lowest possible standard chosen in order to dispose of the question in the most politically expedient manner.
Fiber is proven technology and remains the most obsolescence proof advanced telecommunications infrastructure going to best accommodate the growing volume of bandwidth hungry applications and multiple services.