- break compability or make their sites slow in other browsers, sometimes in so interesting ways that it makes it hard to defend as just incompetence. Edit, example: didn't they go out of their way to find a way to make YouTube crawl in Firefox while performing well in Chrome a few months ago? IIRC instead of doing it the new straightforward way that was supported everywhere they went with a solution that was so backwards that it was already deprecated in Chrome as well or something?
- make banners on the front page of the worlds most famous web property, urging people to change