While primary sources are the gold standard, they are not are requirement on Wikitree, sometimes secondary and subsequent sources are all that's available.
When adding a new profile Wikitree even provides a tick box for "unsourced family tree handed down to...."
As long as you have evidence that these people actually existed you can add them to Wikitree, further and/or better sources can be added as they come to light.
The index may not be ideal, but it's evidence, even Govt birth, death registrations are secondary sources, I've yet to find a copy of the original document filed in the Registry in any jurisdiction that is the primary source, but Registry entries are often cited as a source.
As a profile manager I routinely get other Wikitreers add sources to profiles, and contacts from people not on Wikitree providing information and sources, that's one of the big advantages of Wikitree.
