it's too bad, because [...] It's a pre-commitment, limiting your options

Pre-commitment is only necessarily bad in for perfectly rational agents in one-player games without akrasia. In multi-player games (the ones where CDT doesn't work, e.g. Parfit's Hitchhiker), or if you have akrasia (which can be described as you acting as a different player than yourself at a different time), pre-commitment does win in certain situations. That's the whole point of picoeconomics, including pre-commitment devices such as Beeminder.

Plus, alcohol is not such a strong pre-commitment, anyway; it makes you less shy, but if you're really motivated not to do/say something, then alcohol won't make you do/say that.[1] If anything, it's a pre-commitment to not perform activities needing good reaction times and coordination such as driving.