All of these same things were said about Paula Welden when she went missing from the Long Trail near Bennington College in 1946: she was running away from something, left to start a new life in Canada, had a secret boyfriend she was meeting, was depressed and went off to do the old squaw walk in the cold woods, etc. And guess what? There was nothing to any of it. Police zeroed in on a suspect immediately and kept an eye on him for decades but were never able to build a strong enough case to charge him. This happens ALL THE TIME.
Whatever Maura was TRYING to do is irrelevant, as she had an accident and didn't reach her destination. (And what this destination might have been, nearly 14 years later we still don't know, which indicates strongly that she was traveling alone.) She fled the scene on foot and despite an exhaustive search, no evidence was ever found that she went off the road at any point. Ergo, the most likely scenario is that someone picked her up, that this someone was a stranger (again, no evidence she was traveling with anybody), and that this stranger probably killed her and disposed of her body.
That's not leaping to conclusions. That's simply what the optics of this disappearance point toward as being the most likely scenario.
p.s.
For the record, I'm not endorsing Claude Moulton as the responsible. But he can't be ruled out and he has a documented history of violence and impropriety with young women /teenage girls going back to the 1970's.
What Maura was trying to do is not irrelevant when you are dealing with a missing person who had a history of theft and alcohol abuse. When she just a couple days earlier wrecked her dad's car (likely because she was driving under the influence) and she got into the accident the night she disappeared likely because she was driving under the influence again. At that point if she was found she was probably facing jail time. Probably would have been kicked out of her second school.
Maura was an avid hiker and I believe it is said that she knew that area well. If she wanted to create a situation where it would be hard to ever find her she would probably know how to pull that off.