User blog comment:Stevethebarbarian/What I DON'T want to see in HTTYD3/@comment-5690373-20151101002910/@comment-24990845-20151109093130

Because Toothless' blast disabled some "biological" parts of the Bewilderbeasts. That help control the dragons. it may even be thought as it stunned the Bewilderbeast's brain so it couldn't concenrate. But those are just therioes. Hiccup mentions dragon's loyalty. The dragons didn't want to be in control, so after Toothless got them out, they were loyal to their new "alpha".