My wallet will either: not send zaps at all or double send zaps. Either case causes unnecessary friction to social engagement.
Aside from that, an emoji reaction conveys some meaning, a zap conveys value.
Discussion
A double spend in an interesting issue, which wallet are you using?
A reaction tells me nothing, they are broken because I am not a social media platform mining data.
See reactions dont even show. 
Mutiny wallet, hasn't been great thinking about moving back to Phoenix.
You can opt out, it doesn't change that 🤔 means something different from ❤️ or 💪🏻.
Emoji reactions convey differences in kind, zaps only convey differences in degree.