Arthur Conan Doyle, through Sherlock Holmes in the collection "The Sign of Four", wrote "[W]hen you have eliminated the impossible, whatever remains, however improbable, must be the truth". We have almost no idea what is impossible in this case. We know that 2 healthy teenage girls were dropped off at 1pm on February 13, 2017. We know that at 2:07pm one of them (Libby) took a picture of the other (Abby) while she was standing on the Monon High Bridge. We believe this picture to have been taken just southeast of Deer Creek. We believe that around 2:30pm, a picture was taken by one of the girls on Libby's phone of the "bridge guy" who police have named as a suspect. We know that the girls did not return for their pickup, and were reported missing around 5:30pm. We know that their bodies were found at approximately 12:15pm on the next day, February 14, roughly northeast from their last known position (the 2:30pm picture on the bridge). It has been reported above that girl's clothing was seen in Deer Creek.
It has been reported that the girls were there to hike, which appears to be a common pastime in the area, and while there could be other reasons, we don't know them with any certainty. We don't know time of death, cause of death, or potential suspects. We have a very poor picture, in which nearly every type of clothing or accessory has been seen. We have an extremely short voice clip which isn't even confirmed to be the same person as the picture. It does appear that he is white and male. We don't know how a possible lone individual managed to control two teenage girls. We don't know if there was only one person. Was he armed? Was he acting as an authority figure? Was one of the girls injured (by accident or on purpose)? We don't know. We don't know if LE have any DNA evidence, though we do know that multiple agencies are involved, and that billboards have been placed nationally.
In short, the only things that we know are impossible are by my reckoning: 1) that the murders could not have been before 2:07pm on February 13 and 2) that the murders could not have been after 12:15pm on February 14. That's it, as far as I can tell.
LE has a different goal than we do at present. LE wants to catch the perpetrator and ensure that he is convicted, while our primary goal seems to be to catch this person. LE is not infallible -- their strategy may be wrong. It is possible that releasing more information could bring the perpetrator to justice more quickly, but their experience suggests that this is not the case. LE wants to make certain that when this person is captured, whether he gets life or death, he dies (after years rotting in jail or having exhausted all appeals) in a small room with cold concrete walls, surrounded by people who hate him.
I think that's an important thing to remember. I agree with you that it's important that we not demand more information when LE has declined to give it. I also think it's important to remember that most of the people here just want to help. Of course, this is all just my opinion...