> Why would one want to ignore beneficial knowledge received in the form of tradition?
You want to be skeptical of tradition as a source of factual information because, while there exists beneficial knowledge that may be received in the form of tradition, it is impossible to reliably separate it from harmful false "knowledge" received in the form of tradition, without first turning it into knowledge derived from structured scientific information gathering.
> it is impossible to reliably separate it from harmful false "knowledge" received in the form of tradition
Evolution/Survivability of a group usually takes care of that
Yeah, slightly harmful/long term harmful things will go though, but not major things.
Someone discovered cheese with mold is edible (probably happened in a low food situation), but there's a high likelihood on people having tried other things with mold and it didn't work out as expected.
A thousand years ago, it may have been more dangerous to send three times as many villagers to collect water from the river 20km away so that the village would have enough water for everyone to wash their hands, than to have people not wash their hands before eating. The benefits of a practice/tradition can vary over time.
Lots of people may have died from avoidable diseases, but lots of people may also have avoided death by bandits, wild animals, and starvation. (due to more workers allocated to water collection than food production; the extra food produced may have been the difference between life and death during famines for some people.)
Because the past had proportionally more hucksters to scientists than today. And because a lot of that 'ancient wisdom' was invented later, by the aforementioned hucksters:
Because tradition isn't knowledge. While tradition could be (valuable) source of leads, everything inside must be tested, experimented on and see why it does or doesn't work.
That article is perfect example - lots of cultures have fasting. We look at the fasting results and we find something interesting about how out body works. Now we have knowledge that we can build upon.
You want to be skeptical of tradition as a source of factual information because, while there exists beneficial knowledge that may be received in the form of tradition, it is impossible to reliably separate it from harmful false "knowledge" received in the form of tradition, without first turning it into knowledge derived from structured scientific information gathering.