> Wiktionary reuses OED content? I'm surprised the OED allows that.
Facts (etymologies) are not copyrightable. The exact same text can't be used of course, but it can be rephrased, or to some extend quoted under "Fair use".
Why is not reliable? The same has been said about Wikipedia for long time, but for some reason Wiktionary still does not get the same level of trust as Wikipedia. A lot of the etymologies on Wiktionary come from reputable sources such as the mentioned OED. In some cases there might be multiple conflicting sources and theories, and such complex cases are likely misrepresented by the automatic extraction tools.
Facts (etymologies) are not copyrightable. The exact same text can't be used of course, but it can be rephrased, or to some extend quoted under "Fair use".