Captcha has become very difficult to solve. I can think of two reasons for this:

one: similar to banning someone, increase the difficulty rating of their captchas to they spend enormous amounts of time trying to comolete the captcha and commenting becomes very difficult, so difficult that they might abandon their task.

two: captchas are just more difficult

lately the captchas have become more and more grainy: I have to zoom in to make out the blurry outline of what might be a car. The captchas alternate between different solving types, and some are far more difficult than others, or require far greater patience(e.g. the captcha frames that, once selected, slowly fissolve over the course of 5 seconds. when you have to select 10 correct images that's 5 seconds of refreshing apiece, plus zooming in to be able to even try to make out the blurry images. Then you must have missed one [?!?] because it wants you to do it again.

Now escuse me while I go spend more time solving the captcha than I did typing this out and selecting an image.

So...the math/science bit: captcha difficulty vs. time is up