That's true. It's useful in that it's a lot more sensitive to driver issues that might not show up in the games you do play. However, the benchmark uses a proprietary engine that is not used in any game on the market. I believe 06 adds some heavier CPU testing so that multi-core setups (SMP and dual/quad core) can be tested to some extent. Along with actual games, 3DMark isn't bad, but we don't use them in benchmarking simply because of the proprietary engine and that there is, like I mentioned earlier, no game (except whatever tech demo game the full, i.e. paid, versions) that actually uses the 3DMark engine. AFAIK, it's not open to that possibility, but don't quote me.
I do like it for the fact that it will hammer your video card, which is certainly useful when overclocking.
Now, I'm not saying don't factor in 3DMark at all, but don't rely on those results exclusively. Keep benchmarking, but don't get caught up like some people do in trying to grab the 3DMark eWang Maximus score.