Several stories – indicating that the concern about libation wine was real for them. For example, a person’s lulav touching his wine. Or the extreme case of an infant touching the wine (as an example of intent not being the more key element here in declaring wine for libations. Plus, conversions with circumcision and dunking in a mikveh. Plus, the impurity factor, given that status. Note the stringency here, especially given the biblical prohibition. Also, a greater concern that converts who have completed the process are still subject to their original beliefs… or a year or so. Plus, concerns about taint of partial converts with regard to the wine.