The Cunctator, 18/06/2018 17:57:
Is there a coherent explanation of what content
Wikidata is extracting from
CC-BY-SA projects?
Not really, because it's a very distributed and long-running process
(which is very very far from completion). But there are some relevant
examples explained in some publications.
https://eprints.soton.ac.uk/412922/1/opensym_wd_vs_wp_2_.pdf
https://eprints.soton.ac.uk/413433/1/Open_Sym_Short_Paper_Wikidata_Multilin…
http://oadoi.org/10.1145/2872427.2874809
Your claims that the abusive destruction of copyleft
by the Wikidata
project have nothing to do with copyright and nothing to do with Wikidata
don't make any sense.
By "abusive destruction of copyleft" do you
mean the practice of
mirroring Wikipedia articles, or snippets thereof, without really
complying with the copyleft licenses?
The first large scale example (which went way beyond the usual rogue
mirrors) was probably Facebook with "community pages" in 2010.
<https://lists.wikimedia.org/pipermail/wikimedia-l/2010-April/104232.html>
At the time, the Wikimedia Foundation attempted to get them include a
visible reference to CC-BY-SA, links from which the history and edit
buttons would be visible, and so on. Some considered the result
acceptable, some didn't. But many said there was no way to enforce
something else.
Free riders are a common and well-studied issue of copyleft projects.
The countermeasure is generally some kind of copyleft compliance
syndicate, like
https://sfconservancy.org/copyleft-compliance/principles.html
Federico