So many errors in that article... I caution you against drawing any conclusions from it.
To be clear, in "Apple speak", Fast charging means an iPhone or iPad that can draw power at greater than 10/12 watts, which will of course reduce power time when charging from 0-50% battery.
Since no Apple devices allow a draw of greater than 10/12 watts via USB-A cable, by nature, "Fast charge" must be delivered via USB-C cable/brick, and must have the associated USB-C PD chip inside the receiving device (which the 7/7 Plus does not have).
In the article linked above, the author erroneously reports that the "Apple 29W USB-C adapter, which can do 14.5V @ 3A", which should be 2A. He goes on to repeat this error several times, wondering why he never sees 3A draw. Because the neither the phone supports 3A, nor does the charger! He also never measures the wattage draw a <50% charge, only relates his charging time. I imagine if he were to measure, he'd see something >11.6 watts on the 8/8 Plus. Something that would be impossible with a 7/7 Plus.