The headline is slightly click-bait. Most the work is outside slack - parsing Craigslist, classifying etc.. The slack channel bit is one part of the puzzle. The article itself says there are 4 steps and devotes 2 paras to slack.
I guess the author chose slack in the title because it will result in eyeballs rather than saying how he used Python, craigslist because they aren't "sexy".
I guess the author chose slack in the title because it will result in eyeballs rather than saying how he used Python, craigslist because they aren't "sexy".