but, we can be individually set to "Don't block", "Alert", "Block and notify" or "Block silently"
why by default is set to "Don't block"?
because, it's for advanced users. which want modify many settings with details.
the function of that is protecting us from suspicious websites when we browsing on the net.
for me, I set to default and No problem.
hopefully my answer is what you want to know.