Appart from the fact that the Behavior Blocker is an old feature and it's usefullness is very limited in today's Windows environment. It is a blocker of suspicious behavior (thus preventing an unknown virus to spread).
Almost all the actions on your computer are performed by .exe files. If you prevent .exe files from executing their actions (such as opening a file for writing), you block almost everything - Word won't be able to write the .doc file, e-mail client won't be able to save the downloaded e-mail, programs won't be able to store their settings. The operation "opening a file for writing, performed by an .exe file" is very common and there's nothing suspicious about it. On the other hand, the operation "opening an .exe file for writing" is much less common and more suspicious (actually, I think it's even more suspicious when it's performed by a file with .xyz extension - that cannot even be started in an ordinary way - than by an .exe file). It will prevent files (like BAT,VBS,WSH,SCR,EXE...) to execute their actions.