Because people accept a EULA when they give their data to FB or Google. Github is exploiting a grey area to leverage a big fat chunk of GPL (or other) licensed

Because people accept a EULA when they give their data to FB or Google. Github is exploiting a grey area to leverage a big fat chunk of GPL (or other) licensed code in ways that are perceived to be a technically probably legal, but morally very ambiguous understanding of these licenses.