Firefox shrugs its shoulders and regards the /div
as equivalent to /title, which is more helpful to the end user, but
fails to alert the originator to the structural problem in his code.

To be honest that's not the job of the browser. A browser should
attempt to work arround broken code (theres a lot out there), or fail
with a warning (code broken), not give a blank page.

The author should use (two clicks with the web-developer extention in
firefox) a validator, which quckly reports "Failed validation, 33
errors".