Chrome gives nice warnings when passive listeners are not used[1]. This is demonstrably[2] causing people who have not used passive listeners / may have written poor code in the past in the past to take note and use them. It works.

1. https://developers.google.com/web/updates/images/2016/10/avo...

2. https://github.com/search?utf8=%E2%9C%93&q=non-passive+event...