Perhaps I was a bit strict, but Wikipedia is mainly meant to cite secondary sources.

When they explain where primary sources are allowed, they emphasize they "should be used carefully":

https://en.wikipedia.org/wiki/Wikipedia:Identifying_and_usin...

Also "Wikipedia articles should be based on reliable, published secondary sources, and to a lesser extent, on tertiary sources and primary sources."

https://en.wikipedia.org/wiki/Wikipedia:No_original_research...

The general idea is that primary sources have not been judged as notable by anyone. The fact that a secondary source considers it notable to include a primary source is a strong signal that the information has passed a first, minimal bar for inclusion in an encyclopedia.

And when primary sources are cited, Wikipedia is exceptionally clear that they must be cited only for verifiable statements of fact, not interpretations or synthesis. That's what secondary sources are for.