What would the average responsibilities be like for a staff of 300 people at Wikipedia? I was under the impression that the core of its usefulness (the content)

What would the average responsibilities be like for a staff of 300 people at Wikipedia? I was under the impression that the core of its usefulness (the content) is done on behalf of volunteer work. On the other hand, as useful as Wikipedia is, if it were to disappear couldn’t we all just use and donate to Marginalia.nu for our obscure factoids, references and summaries?