Google's 2014 net income was $14B. Chrome is one of the most valuable properties that Google owns, as it allows them to control a large fraction of advertising

Google's 2014 net income was $14B. Chrome is one of the most valuable properties that Google owns, as it allows them to control a large fraction of advertising on the desktop, and advertising is their core business. They can afford to hire thousands more developers to vet Chrome extensions, yet they don't - implying that at least the upper levels of the Google command hierarchy don't consider this to be a problem or don't care about fixing it.