So my guess this has to do with article's author personal experience on his/her country implementation of technology.
Often you can tell that your phone is about to ring before the phone even begins to vibrate or chime.
https://www.quora.com/Why-do-speakers-make-noise-when-mobile...
There is a high likelihood that this isn’t a problem now and hasn’t been a problem for some time; but it might be wise to err on the side of caution if you want your pilot not to have to repeat or request repeats of radio information.
And once you’re in the air your phone will frenetically try to connect to a cell tower, absolutely murdering battery life. So you should turn it off after take off anyway just for your own battery sake.
However it could just as easily be spectrum oversaturation, so if 10% of passengers disobey there's no issue, but if 100% of passengers disobey then they have to start restricting phones on planes.
Air travel feels draconian enough, I'm willing to just comply, since this compliance benefits my battery-life anyway I'm not going to split hairs. I would like to bring water with me though.
edit: 2G was also digital.
Otherwise Al-Qaeda would've dropped the entire Western planes by smuggling cell phones in luggage of unsuspecting fliers.
And there is plenty of evidence people forget their phone on by mistake. You draw the conclusions.