It's just all too embarrassing. There are several theories as to what happened. The cost of switched connection calls, the technology competing with Internet faxing, has fallen drastically. Despite all the man-hours invested in attachment standards, computer software has never found a simple way to preserve and transmit complex formats, such as forms. Scanners and optical character recognition have never gotten smart and simple enough for a seamless takeover.
Documents prepared on the desktop are just one degree more problematic.
Until recently it was hard even to figure out a simple way for a desktop to receive faxes. The problem has been addressed fairly recently. Faxes sent to the number end up in the client's e-mail box. Ultimately what makes faxes a climax technology is their degree of integration into the minutiae of everyday life. They just naturally incorporate themselves into our everyday habits.