I watched the first 411 documentary but have not seen the new hunting one yet. That being noted I do not think people go missing due to aliens or bigfoot. They either want to be missing, they die and disappear due to nature decomposing them, they are murdered and hidden, or scattered after being the victim of a non human predator.
I was fortunate to be taught at homicide school by a detective who worked 25 years of his career at LAPD in homicide. He told me to go to every suspicious death during my first year in homicide, as people "die in weird ways". Even though i had almost two decades seeing homicides, murders, suicides, and accidental deaths in uniform, I took his advice and lived death investigation every week for a year. That did not include later working on almost 100 homicide investigations. People do die in very weird ways was also my conclusion. And that was in a metro area. How about the guys who investigate crimes in the sticks? Or work SAR? Weird shit happens, even in the boonies, maybe even more so...
Look at Southeast Asia and the Vietnam War. We can have a lat/long for a downed aircraft, or where a recon team called for xtraction while being overrun, or where a pilot parachuted into the jungle. And they just vanish. Shot, killed, buried, and part of the food chain. We are still sifting dirt, reading old records, and interviewing locals to find our dead and missing. 50, 60, and 75 years after the fact. WW2, Korea, Vietnam, does not matter. What do we recover? Buttons, zippers, bone fragments, and teeth. What is the difference between the rural forest in Northern Idaho and the the rural jungle in Laos? nothing. They both hold their secrets close to their chest is all, making you work for your answers.
Documentary makers like to sell documentaries. I have never seen one yet that did not leave out facts that would be detrimental to their view, angle, or might debunk their movie. Every coin has two sides, and every death or missing person has a logical but perhaps bizarre explanation.
Enjoy the entertainment, then get back out in the woods where you belong.