In addition to increasing the gap, you have to drive steadily, with no braking. This makes you become the most predictable car on the road, people behind you can follow steadily instead of constantly accelerating & braking. This leads to reduced congestion.
There is no steady in high congestion areas with lots of on and off ramps. The rules are nice when there is no congestion and plenty of room to spread out, but the problems are inevitable at rush times or at chokepoints.
Not all congestion are created by those chokepoints. It's created because someone at some point hit the brakes, and then cars behind get into a pattern of accelerating & braking constantly until the congestion resolves. Steady driving with lots of gaps helps resolve this faster and prevent congestion in general.
This CGP video covers some of this https://www.youtube.com/watch?v=iHzzSao6ypE