<p>I for one think something (accurate) is better than nothing, so it should make a difference whether something's there yet. However, a counterargument: people might feel less welcome to change something short that's already there, even if it's incomplete.</p>

<p>The accuracy of the information should matter more than the source (all quotation and attribution being proper and equal, that is). I think I understand the desire to avoid copying existing info without improving it, but improvement isn't always possible, and degradation shouldn't be preferable to copying in such cases.</p>

<p><a href="https://stats.meta.stackexchange.com/q/372/32036">What to include</a> seems to me like the broader, more important question; if Wikipedia or Wolfram or 4chan can provide all the desired information in a succinct, thorough, accurate manner, why should anyone care where the info came from (so long as it's cited properly)? Conversely, where the info came from should not affect how the edit's quality is judged when it's lacking either. As others have implied, Wikipedia is only as reliable as us <a href="https://en.wikipedia.org/wiki/Wikipedia:Wikipedians" rel="nofollow noreferrer">Wikipedians</a>, and our reliability varies quite widely.</p>
