Thank-you for being patronising. I did not say that I waste hours every day editing Wikipedia.
In fact, 'outreach', telling the public about your field, is an increasingly important part of what academics are supposed to do. Sometimes that will mean arguing with uneducated people. The aim is to educate them, at least a little bit. And contributing to one of the world's most frequently read websites isn't really what I'd call "low impact".
As for defending content: in most fields, it's not that big a problem. How many 15 year olds care about the poisonous chemicals in tomato plants, or surface catalysis, or the particles of the standard model? Only a few fields (climate change, evolution, etc.) are likely to attract the sort of controversy that requires constant vigilance, and I'm sure there are enough people already guarding those against unwanted changes.