He sort of said that. Perhaps what you were referring to was the Kalama Sutta:
“What do you think, Kalamas? When greed arises in a person, does it arise for welfare or for harm?”
“For harm, lord.”
“And this greedy person, overcome by greed, his mind possessed by greed, kills living beings, takes what is not given, goes after another person’s wife, tells lies, and induces others to do likewise, all of
which is for long-term harm & suffering.”
“Yes, lord.”
“Now, what do you think, Kalamas? When aversion arises in a person, does it arise for welfare or for harm?”
“For harm, lord.”
“And this aversive person, overcome by aversion, his mind possessed by aversion, kills living beings, takes what is not given, goes after another person’s wife, tells lies, and induces others to do likewise, all of which is for long-term harm & suffering.”
“Yes, lord.”
“Now, what do you think, Kalamas? When delusion arises in a person, does it arise for welfare or for harm?”
“For harm, lord.”
“And this deluded person, overcome by delusion, his mind possessed by delusion, kills living beings, takes what is not given, goes after another person’s wife, tells lies, and induces others to do likewise, all of which is for long-term harm & suffering.”
“Yes, lord.”
“So what do you think, Kalamas: Are these qualities skillful or unskillful?”
“Unskillful, lord.”
“Blameworthy or blameless?”
“Blameworthy, lord.”
“Criticized by the wise or praised by the wise?”
“Criticized by the wise, lord.”
“When adopted & carried out, do they lead to harm & to suffering, or not?”
“When adopted & carried out, they lead to harm & to suffering. That is how it appears to us.”
"So, as I said, Kalamas: ‘Don’t go by reports, by legends, by traditions, by scripture, by logical conjecture, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, “This contemplative is our teacher.” When you know for yourselves that, “These qualities are unskillful; these qualities are blameworthy; these qualities are criticized by the wise; these qualities, when adopted & carried out, lead to harm & to suffering” — then you should abandon them.’ Thus was it said. And in reference to this was it said.
That was a key phrase not to miss there: And in reference to this was it said. There are a couple of other places I recall where the Buddha actually recommends (or at least does not object to) following ancient traditions, which don’t even appear to be all that Buddhist, when they have the virtue of being helpful and wholesome somehow. One example is here.
So I think the take-away message here is that sometimes ancient traditions should be followed, and sometimes not, depending on how wholesome or wise those traditions are.
I think you are correct that ancient traditions should not be automatically assumed to be correct, and we should just follow them blindly, effectively lobotomizing the rational, logical parts of our brains.