According to [[primary source]], the term is specific to historical scholarship, which doesn't include science. I don't know of any Wikipedian who seriously challenges the validity of published peer-reviewed scientific papers as sources for articles.
In which case, [[primary source]] is wrong. A source is primary if it isn't based on any other source - that definition holds for any field.
There aren't many Wikipedians that challenge the validity of any primary source as a source for an article - you simply have to be very careful with how you use them.