Genjutsu is a big thing in the Naruto series. Why does not a single friend of Naruto or Boruto use this power?
Genjutsu require precise chakra control in order to manipulate the target's senses and advanced intelligence to make the illusion convincing, prerequisites that even someone as skilled as Jiraiya lacks. The ability to use Genjutsu is greatly enhanced if someone possesses the Dojutsu eyes. However, there are shinobis who are specialist in this field like Kurenai Yūhi being regarded as one of Konoha's great user of Genjutsu without possessing Dojutsu eyes.
Experting Genjutsu is no joke and it takes years of practice to hone the skill and worst thing is that your teammate might be affected if it goes haywire. It was evident with the case of Yakumo Kurama who was trained under Kurenai but because she couldn't control the jutsu, she was ceased to be a shinobi:
because of Kurenai's natural talent for genjutsu, the Third Hokage tasked Kurenai with helping to train Yakumo Kurama, another talented genjutsu user who longed to be a ninja. However, because Yakumo couldn't control her illusions and thus endangered those around her, Kurenai had to seal away her ninja abilities, preventing her from ever becoming a shinobi.