Funny that they're saying this now because fermented drinks used to protect people from health issues when the water supply was not clean enough to drink.
With beer, this was because the brewer needed to boil the water used in order to kill off any microbes which would compete with the yeast, or it would go "off". It's a very important step for brewing beer. Then the beer would be stored in barrels/casks to help reduce the chance of introducing further microbes, plus the use of preservatives like hops to help keep it longer. With wine, people generally mashed the grape…
For a limited time. The live cultures and then alcohol in fermented drinks keep the bad bacteria at bay.
Keep in mind in the past, not everyone had a convenient source of heat in their homes.