There’s also the possibility that the true love potion gave Emma unusual powers in Storybrooke (and in my mind, will continue to since that’s the magic permeating the place now.) Perhaps normally parent/child love ISN’T usable but because the magic in Storybrooke is basically designed to respond to Emma, it worked.
Regina seemed pretty shocked, which suggests parent/child love would not have EVER worked in the Enchanted Forest.
Then we just have the fact that Rumpel’s story with Baelfire preceeds every thing else in the timeline by centuries. Types of magic can apparently come and go (they couldn’t make more magic beans, they can’t make more enchanted trees). Perhaps True Love’s kiss was not a power that existed at the time.