My mum let me ride my bike with no helmet on. This was common in the 1980s, people didn't worry about it. Fortunately I did not become an accident statistic neither did my brothers.
Plenty of other children did though.
If something has been proven to be unsafe due to better research then why carry on doing what people used to do before they knew better? Once upon a time people thought it was ok to smoke in pregnancy, now we all know better.
Cows milk contains a lot more salt than breastmilk or formula breastmilk substitutes and more of other substances too. It is too much for immature kidneys to handle. It also does not have the right nutrients and does not have enough iron. It can cause internal intestinal bleeding in a small percentage of babies which can lead to anemia. Boiling it will kill bugs (although milk has already been pasteurized so this is not necessary) but it will not change the nutritional profile.
Human babies need either human milk or a safe alternative (formula) until they are over a year old and able to enjoy cows milk as part of a balanced diet. I don't care what they did in the old days when people also dipped the baby's dummy in some brandy to make it sleep