These kind of gamification methods to drive engagement are dark patterns driven by the need of advertisement companies to capture user attention.
Up and down voting was originally not invented as a feature to drive user-engagement or signal approval, but as a way to crowd-source link curation in an largely non-moderated internet forum. I think it is good to keep that original function in mind and design the features around that. So looking from that perspective it is better to have votes anonymous I think.