"Once USCIS approves the I-130 petition, the immigrant visa is available and there is no longer eligibility for K status. Since your immigrant visa petition has been approved and an immediate relative visa is available, your spouse no longer requires the issuance of a K-3 visa to await adjudication of the immigrant visa petition. Therefore, your I-129F visa petition is denied."
Correct. By law, the K-3 is meant to come to the US to await I-130 approval. They can't administratively close an I-129F for no reason. I think by regulation, USCIS must issue a NOID before denying any petition unless you no longer qualify (like in our case). Now, who knows if it actually helps or not. I did see someone post that on Lawfully that the average time to denial for an I-129F for K-3 was significantly less than the time to approval for an I-130. If you assume they were denied due to approved I-130, you can deduce that the K-3 helped to some extent but those are a lot of assumptions and Lawfully is probably a small sample size too.