Because he knew that they were illegal.
Also, the decision to revoke the order prohibiting agencies from working together was portrayed as an effort to make it more difficult for Trump to destroy the evidence. That’s obviously false since there was no evidence. What he was really trying to do was cover up the fact that they’d been violating the executive order all along. Because that would have implicated him.
The article says - “At the time Obama suggested to Yates and Comey—who were to keep their posts under the Trump administration—that the hold-overs consider withholding information from the incoming administration”
They did withhold the info from Trump, but they shared it with the New York Times and others - repeatedly. This is a fact and the author agrees.
“They put damaging the incoming Trump administration above protecting the country from purported Russian agents.”
Obama changed the rules to share certain “intelligence” with multiple agencies making it harder to trace the origin of the leaks as you said.
While it is possible that some of the “actors” did not realize they were cogs in a big wheel they could not see, they still shared the same goal - to damage a duly elected President.
How do you protect an investigation when you are leaking the guts of the investigation (the Steele dossier) to the media and leaky politicians? Their own actions undermined the idea and demonstrates the real goal was to harm Trump. They succeeded.