@chiffchaff: "sometimes preparatory lemmas are required, even preparatoy fields of study, that may require suspension of curiosity until those lemmas are established."
Exactly this. The more nuanced take re Buddhism seems to be that Buddha did not categorically refuse to take up any particular question. Rather, he might answer or not, considering the questioner's readiness. https://groupworksdeck.org/patterns/Seasoned_Timing