Well she might be a malicious individual who enjoys upsetting parents, wasting the time of professional colleagues and also limiting her career by eroding their trust in her judgment.
Or she genuinely felt some concerns for your child and did what she thought was right, even if we now know that there were some misunderstandings.
Ultimately, she was concerned and made a referral. Of course you didn't like the experience, but your child is her prime concern so, as she was worried, she did the right thing. The system, in this case, worked. Because SS visited to assess the situation, were satisfied, and that's the end of it.
Some of your responses on here have been a bit unusual - criticism of her for wearing a sundress, not wanting to reveal what the concerns were, paranoia about revealing details and then posting details of your health board. So maybe there were some unusual behaviours in rl too, or maybe your communication and conversation wasn't clear or raised some flags on the day. Are you ND, like your daughter?
Ultimately, HV sees a lot of 4 year old kids and knows that they often pretend to be animals. Despite this, she had concerns about your child. Referrals are not just made for concerns, but also if they think a family needs help.
I think it's better that they refer when worried than just shrug and think it's probably ok.