That states you can go up to 4 meters and maintain a 5A rating (though you would drop to USB 2.0), according to that chart, while with USB 3.1 you can also do 5A at 2 meters or less (roughly 6 feet ish on the longer end) and still maintain thunderbolt transfer speeds.
To be more specific, the power handling is more based on the wire gauge being utilized than anything else, while the length is more important for speeds. PD standard as a whole currently is a maximum of 20 volts DC with a maximum current of 5 amps, this is what derives your 100W cable. As long as the cable can dissipate that kind of heat without burning up you are fine and I have found lengths up to 6ft (which supports your table). Anker just has not released it yet I am assuming.
I can also state that I have made 50 ft long cables for testing product at my company with 18 gauge wires that are running 28 volts at around 3 amps of draw, so wattage really isn't the issue.