Hecate does scold the witches for interfering with Macbeth in matters of death. This suggests that they did affect his behavior.
How did you dare
To trade and traffic with Macbeth
In riddles and affairs of death; (Act 3, Scene 5)
Macbeth apparently was influenced, at least partly, by the sisters—toward murder.
Hecate seems to imply that Macbeth has free will when she describes him as a “wayward son.”
And, which is worse, all you have done(10)
Hath been but for a wayward son,
Spiteful and wrathful: who, as others do,
Loves for his own ends, not for you. (Act 3, Scene 5)
A wayward son is someone who does not do what is expected of him. This suggests that Macbeth did not do what the Weird Sisters expected him to do.
Hecate goes on to suggest that she is going to take over, and royally mess with Macbeth. She has big plans to use illusion to “draw him on to his confusion.” Whatever has been his idea, and whatever has been suggested by the others, she plans to get involved. She will give him visions that will confuse him and make him overconfident.