Sorry... I searched for it, but for the life of me I can't track it down. I think the original article was talking about DuckDuckGo and Google; the "strength" in that case was Google's information-gathering: Google's bottom line is partially defined by using the information it records about its users to drive advertisements and other usability tweaks (such as marking search results with stars, etc). By focusing on privacy, DDG "attacked Google's strength"--Google can't compete with DDG on privacy because it's precluded by what Google does best.

You can obviously frame "lack of privacy" as a weakness of Google, but the important part is that it's a weakness that can't be addressed without huge changes to work around their established strengths.