It's hard to say whether Wikipedia is more or less powerful in its 'societal sway' than traditional encyclopedias of years past. It's free and certainly more accessible, which allows it to reach a broader audience. But it's also written and edited by many contributors of various backgrounds, where encyclopedias probably underwent thorough editing (and most likely have a consistent bias). Encyclopedias and similar resources were pretty limited too, as a person could only really access an encyclopedia set they owned or could access from their local library. Now we have access to all types of information with a variety of biases and viewpoints, putting the power in the hands of the researcher as long as they're smart about how they're getting their sources.