There is a tag for elf/elves but not for dwarf/dwarves.
Should one be added?
Looking at the elf and half-elf questions (there are only five between them, all of them from 2011), some of them seem like the tag is unneeded and some it's arguably appropriate. I imagine that if they'd been made today, the tags would have been removed; the site's policies have evolved since then.
Just because there's a tag for one thing doesn't mean we need tags for all complementary things as well. Tags don't get made in a vacuum; they're created because there is a need in the community. If you ask a question that you feel needs to be tagged this way after reading up on what tags are for, that's when the tag should be made. Anything before that is jumping the gun and adding unnecessary "noise" to the site.
I don't think we need the elf tag, so I don't think we need a
dwarf tag, as much as I like the stout bearded folk.
The elf tag is only used on two questions, both related to 4e racial abilities, but I don't know what it would help people find. I suggest we consider removing it.
The point of the SE tagging system is to be emergent - to appear as needed to usefully describe and group questions. Therefore we don't create them 'on spec' - they should appear because there's already a set of questions they'd help out.
Furthermore, tags like "elves" and dwarves" are bad from several points of view. There's very little value to clustering a question about Shadowrun elves and D&D elves - besides some nominal similarity, they're different things. So mainly you're using the tag to cluster within games/game groups. The only two "elf" questions are within D&D 4e, but that then makes "elf" a somewhat undesirable meta tag (doesn't stand alone as the only tag on a question). We try not to do meta tags except in very limited circumstances.
The real question is - why do you think there should be? "Parity" with the elf tag is not really a good reason in and of itself.