Why would the police downplay the impact that having all those people on the scene could have on this case?
Because they knew if anyone was ever tried for kidnapping Elizabeth, that person would play up the fact that non-official people were all over the crime scene, contaminating it and rendering any evidence from it questionable.
I have one spot of trouble with what you said about this...from the day the police were called, everyone knew the scene had been contaminated!!
I find it apalling that there was no repremand, if indeed what Dinse said was a fact. It almost sets it up in one's mind of incompetence of the PD.
That is to me, a hinderence in this case. Now the silence on all parts. Did the PD know that night, exactly what happened to Elizabeth, and felt no harm was done with people tramping out and about the house? Could be.