User benn's answer to this question What-plant-is-this-does-anyone-know-name was fine and appears to be correct, but he provided no corroboration for his answer. In the comments, he states that he's grown the plant that he identified for 20 years; this is all well and good, but just stating "It's a yucca" without a species attribution and no citations is really a useless answer to others who may have the same question. And with 20 years of experience, I would hope that they could've added cultural information of their own, rather than a link, such as the soil medium used, watering schedule, watering amount, sunlight, etc. so that the person who asked the question (and any future readers) could have as much success they've had.
So - is there a way to require users to provide some sort of evidence for their claimed answer? Is there a way to encourage this, at least, in the site's policies? Do we even want to go down that route? I'm looking at this from a position of "what's most useful to users of this site", and I find unconfirmed, anecdotal answers - especially those with no cultural information, if appropriate - as not being particularly helpful. Am I being too pedantic here?