Journalists don't provide sources because sources would face retaliation if journalists provided their names. Sometimes this is appropriate if the source is providing information in the public interest and sometimes it's corruption if the source is providing misleading information to benefit themselves. Journalism overall has a long tradition of sometimes benefiting the public and sometimes benefiting those in power - both these help maintain the institution (for good and ill, naturally).
Linking to document on the Internet is a different issue, I think, one I wouldn't comment on.
When a journalist uses an anonymous source, then they are putting their own reputation on the line, rather than that of the source.
Unfortunately, as we've seen, there are no consequences for journalists that manufacture outrage and misleading or outright false facts.
...and so consequently, we've seen many many examples in the last decade of journalists citing "unnamed sources" to deliver "facts" that turn out to be utterly false.
...and so the ultimate issue remains that journalists are rewarded for traffic, not accuracy or truth.
Linking to document on the Internet is a different issue, I think, one I wouldn't comment on.