You are not supposed to be driving slower. You are supposed to be driving in average speed with the traffic. You may have had to slow down in the first place to do this. If you are just starting out, a good rule of thumb is to just leave space between you and the vehicle in front of you; keep pace.
The key is to maintain enough space between you and that vehicle that you can
(1) allow people to freely pass through (they are going to do something crazy to do it anyway if they do not have the space)
(2) absorb traffic waves
It is likely you will not be able to do #2 consistently. But you can let off your gas and not hit the break. Hitting the break is an instantaneous warning signal to people behind you, causing something of a reflex for them to also hit the brake. You are trying to avoid the brake-light wave. Letting off easy generally does not cause as much reaction.
What if you end up in a traffic jam anyway? Leave space anyway. It does help.
Aren't more accidents are caused by people getting panicky as they try to cross lanes of traffic that are closed to them? They force their way in or speed up to get around a bunch of people?
It is all about leaving that space so they are comfortable. Everything begins to move faster. And you are more relaxed in your driving because you are not freaking out at what is going on in front of you, allowing you the freedom to react as necessary to all the other kinds of problems traffic can bring.
Intentionally driving slower over a long distance is a misapplication of the principles. As the article points out, it is all about the average speeds. Frankly, very rarely does anyone get "pissed", and all they do is pass around you. And then they end up hitting their brakes and shifting out quickly. Passing != bad thing; we are not trying to win a race here. I have never been honked at.