Look at the top paragraph.

"...to ensure a full and thorough investigation of the Russian Government's efforts to interfere in the 2016 presidential election, I hereby order as follows."

Also note the word "including" that leads into your quoted point (b)(i).

Yeah, it would be a big fucking deal if the campaign coordinated directly with the Kremlin. That's why this point was specifically stated. But that was just one aspect of the investigation.

If the investigation was JUST about coordination with the Trump campaign, it would seem quite a miscarriage of justice that Mueller was able to bring charges against 34 different people, 26 of them Russians, and three Russian companies. These charges against Russian nationals and companies are NOT for perjury or obstruction, they are for interference in the election. And apparently he could not establish that they were coordinated with the Trump campaign.