To add to that video: https://www.youtube.com/watch?v=4LOVLoWqD7E

Btw, the parts pertinent to our discussion in this video is about arsenic and other contamination in rice and other foods.

He also goes on to make observations about dietary changes in populations in East and far East, but knowing what we know about low-carb diets, those bits may be more controversial. He isn't wrong, he just provides a strong opinion without commenting on other methods of eating healthy =)

All Asians do AFAIK. Also, Indians (and perhaps a lot of south-asians) cook a lot with (ground/) parboiled rice.

Very few medically significant bacterial spores survive boiling temperatures. Clostridium botulinum (botulism) is the common one, and it prefers an anaerobic environment (and other requirements: low salt and low acidity[1] — which is why home fermentation, done properly, avoids the risk) and not a lot of microbial competition, in order to get a foothold.

Even if you ignore the standard recommendations, to refrigerate within 1-2 hours, and to toss refrigerated food after 4-5 days, contamination with less-hardy bacteria is far more likely if the food isn't sealed. You tend to have to go out of your way with unsafe canning[2] or fermenting[3] to get botulism poisoning.

Food contamination is generally the result of airborne or insect-borne or utensil-borne microbes that are far less robust than botulinum. Typical contamination tends to occur after the food has been removed from heat, and has cooled enough so the microbes won't be killed almost instantly. Or, of course, if the food was improperly cooked and wasn't uniformly heated to sufficient temperature in the first place.

[1] https://jfoodprotection.org/doi/pdf/10.4315/0362-028X-42.3.2...

[2] https://www.cdc.gov/Mmwr/preview/mmwrhtml/mm6429a6.htm

[3] https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5032a2.htm

Another reason for doing it is that the bran contains some fat. When you are washing the rice, one technique is to push down with your hand to cause the rice grains to rub against one another. This polishes the rice a little bit more and removes a bit more bran from the outside (including any potentially rancid fat). Unless you have ridiculously polished rice, there will always be a bit of bran on the outside, so it can potentially improve the flavour. I eat a lot of rice on its own (no sauce, etc) and I do find that washing it this way improves the flavour slightly.