Apparently, no one read the article. The primary application of this was for the military. The article is based on research done by DARPA. For military use, lithium ion batteries have way too short of a lifespan and the charge times are too long. Also, they can catch fire and burn for a long time, probably a real problem in a military context.
Flow batteries can mitigate all these issues and they’re cheaper and lighter. They can be made from inexpensive materials that are more readily available than lithium.
Given these benefits, it seems obvious that consumer applications will take off. The original researchers see an opportunity here and that’s why they formed a company.
Your cited lithium ion “20 min” charge time is for super chargers only, and in many cases is actually more like 40-45 minutes. Also, super charging is bad for the battery. In all other cases, you’ll be using an L1 or L2 charger which will take anywhere from 8 hours to 72 hours to charge a vehicle.
And, eventually, the lithium ion battery will lose its range as the battery degrades, making the whole car as disposable as that 3-4 year old smartphone you had to toss because the battery can’t hold a charge anymore. Flow batteries will keep refuel times to the same as they are today, and the material can be recharged up to 10,000 times, a huge improvement over lithium ion. And, the lifespan of your car won’t be literally glued and bolted to the lifespan of your battery.