That might be how worms work, but it’s not going to protect someone from installing a keylogger or a RAT from opening an infected Excel spreadsheet in an email,

That might be how worms work, but it’s not going to protect someone from installing a keylogger or a RAT from opening an infected Excel spreadsheet in an email, for example. That’s much more reactive than proactive either way. Better as a secondary measure for a large business than as a primary measure for a small business.