... I'd like to do some searches to see how my skills profile matches up with the rest of the market.
We only allow searches from legitimate companies who are actually hiring -- and even then, only if they pay to subscribe:
So ... found a company! Paul Graham will be so pleased with you! :)
If not specific searches, then it would certainly be useful to be able to compare yourself to the market. How many other people claim similar skillsets to yours, how many other people are in your area, how many searches that turned you up also turned others - and perhaps then what searches did you narrowly miss out on? Like a Google search summarising the numbers of other answers. If there are 20 similar developers to you in your area, you'll know to try harder to add details that set you apart.
The central premise for careers.so is to try to match people with jobs? Shouldn't it be offering the people the tools to be attractive to searchers.
This isn't (just) about gaming the system. Searchers still need to trust the results and that seekers are not fabricating skills they don't actually have, but the best way of improving your CV is by being told what it isn't showing (but could) or what you might not consider important, but apparently is something that people are currently looking for.