not all did
history of science is likewise checkered, particularly when in partnership with governments but also when afforded free reign.
utilitarianism when applied to people, particularly if there is a belief in eugenics and/or hard racial categories, or “weaker sex” or “babies don’t feel pain up to 9 months” (only officially renounced in 1984 in the USA, used to justify many awful things)
i don’t think it weakens a position to acknowledge what’s been good or ok in “the other side” while simultaneously rejecting it for greater reasons.