Genealogy has grown into a popular hobby, and we have some people who are jumping on the craze, but go about it with a half-hearted effort. I can't blame people for trying to piece their ancestry together, and if they are having fun with it, then that is all that really matters.
Documentation is work, and perhaps that separates the casual genealogist from the serious one.
If anything, people need to explain in their database or publications where they received their information. Even if it is from word of mouth, that's what people must explain. Even for themselves, at some point down the line they are going to question their earlier work. Agreed that documentation is important for the serious genealogist. But the whole Internet genealogy thing would likely not have occurred without the interest of the casual genealogist.