I think that a bunch of things like the JavaScript console, DOM editor, etc. should only be enabled when a browser developer mode has been activated, and such a

I think that a bunch of things like the JavaScript console, DOM editor, etc. should only be enabled when a browser developer mode has been activated, and such a mode would also enable a variety of warnings like this. It shouldn't be difficult to find or enable the developer mode, but it shouldn't be on by default. That way, people who know (or should know) what these sorts of warnings mean will see them without ordinary users getting unnecessarily scared or confused. Hopefully a site's own developers regularly view their own site in the same browser they've used in the past for debugging the site.