NVT OSA is not a security that average user is going to install and configure. This is also true for all default deny software.
It would be good if OSA could be configured and adjusted by a more experienced user, and would run silently on the computer of an average user.
So, the most important thing is finding the way to avoid false positives and eliminate the possibility to block anything that could crush/destabilize Windows OS or block system/software updates.
That will be hardly possible for the universal BB that has a wide spectrum of tasks. Furthermore, most popular AVs have a kind of BB too, that will overlap and sometimes will conflict with OSA. Also, most 0-day executables propagate thanks to malicious scripts/scriptlets and malicious websites.
The average user would gain much if OSA could focus on safe macros/script/scriptlets/sponsors blocking.
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Edit
By sponsors, I mean the legitimate programs used in malware attacks like: bitsadmin.exe, csc.exe, wcscript.exe, cscript.exe, mshta.exe, powershell.exe, etc .