Many Blogger features are vulnerable to security filters. The ability to use Blogger commenting, the EU cookie advice banner won't display or won't go away, the infamous Reading List, the Blogger Stats "Don't track ..." option - all require cookies and scripts, that are subject to filtering.
Any filters, on any given computer, can change, at a moments notice - and without intentional action by the owner of the computer. One common complaint by many computer owners starts out
I didn't change a thing! Commenting / the cookie advice banner / my Reading List / my Stats display just stopped working!In many cases, the owner will be absolutely correct - he did not cause the problem - but he will still have problems with Comments / The Cookie Advice Banner / Post/Page/Template Preview / Reading List / Stats / Template Designer / whatever.