Shooting at a target that moves faster than your bullit.
Intel has been working at making digital radios for more than the mentioned decade.
From a certain point of view, this makes perfect sense, but not so much for WiFi.
The strength of digital radios is that they can shift between radically different radio protocols simply by changing the SW settings.
This would be a great boon to mobile phones since they can then reconfigure to using whatever network and frequencies are available in a given area without the need to include a physical RF circuit for each and every protocol and frequency out there.
So in principle an extremely good idea from Intel.
The problem and the reason they have continuously failed to deliver (and the current implementation seems to be a bit short of a total success) is that they are aiming at a moving target.
The reason RF circuitry is (partially) implemented in analog circuitry is that analog chips are by definition faster than digital chips working on the same chipset technology (so the transistors are identical).
Digital chips need a generation or more of chipset technology development in order to do what can now be done in analog chips.
Radio frequencies are a scarse commodity, so everybody tries to use them as well as possible and to cram as much data into the available space as posssible.
This means that the RF standards are continuously being upgraded for higher speed and bandwidth as soon as there is an available technology than can handle the needed processing.
So digital radios are playing catchup to standards that are continously being upgraded to a level, where only analog radios can follow (yet).
What Intel needs in order to succeed is for RF development to stagnate and reach a plateau, where speeds can no longer be increased by using faster or more powerfull chipsets or where the speeds are simply good enough for most practical purposes.
When that happens, they have a chance of success