imo the killer feature of RES is that it makes it extremely easy to manage arbitrarily many sockpuppet accounts. there are other nice features of course, but the ease of managing multiple accounts always stood out as one of the biggest perks to me.

in the current political climate, it's not hard to see why reddit might be cautious about implementing such features. of course, the real reason might just be that most reddit users don't even have one account to manage.