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Maybe this was done ironically to show what's wrong with the patent system?
Both require adaptation to changing circumstances.
Both have a psychological aspect.
I should get back into playing both...
So you think up a new question, and the spammers break that just as easily. And a new one with the same result. And so on, and so on.
The only way this could possibly work is if few enough people are doing it so that the spammers don't expend effort on cracking your system - It is security through obscurity. If you are trying to create a general purpose anti spammer mechanism that can be widely used, then captchas although not perfect are the best current solution to a nasty problem.
Expecting a web page creator to write for the situation where there are 1/200th of the resources available seems a tad absurd to me.
Disclaimer : I work with web based GIS applications which can consume a lot of memory / bandwidth / runtime if not optimised correctly, [and can still do so even if they are!]