These are very sensitive data that if exposed to malicious hand, will be used to violate user privacy.
So you want those antivirus companies to snoop through your bookmarks and history so they can "look" for a virus in them?
Viruses are such a fad, when is the last time you were actually infected? You have to be very computer illiterate to get one nowadays and those people will obviously not be on brave, they will probably be on microsoft edge or something clicking on the "you have won" banners.
RE: My rationally for why Brave Browser should consider adding a lite Antivirus