At some point between when the tag synonym system was added to ServerFault and now, the reputation requirements to propose and vote on tags shifted. Even before the change we had trouble getting enough users into the voting process to get synonyms done without a Mod doing it. The more restrictive requirements mean that it a lot harder to clean things up, especially in smaller tags where our active users aren't that active. We seem to have enough for proposing, but getting enough votes is now nearly impossible without a mod.
The older rep-system for synonym voting was much more functional. I'd like that older system back, please. At least until the site grows to the point that SO-style abuses warrant it.