No, this is absolutely not true.
Absolutely Not True.
Don't forget the purpose of the line. Common man. All those reason you just mentioned are noise when it comes things likes bowl games.
A very meaningful line can be made for sure, it can begin the process of increasing a handle, or even keeping the handle down by sidelining certian types of bettors.
The lines will move, things will be inefficient and if you know how to cap it it's like any other issue out there, get your EV and run.
You have take advantage of the extra money in the marketplace that throw the lines out of whack. The books sure as hell do.
As far ass the rest of the post, I don't agree. You sound naive to the game even though you've been around a long time. Too much talk about guessing and offsetting original thoughts. It's times like these that subjective bettor can get burned. He runs too hot or too cold and emotions short circuit rational thinking. That's another although related topic.
It's about discovering which pieces are relevant, which are not, and weighing them properly. There are a lot more pieces that are not relevant, that's for sure. You named many. Like I keep posting...the players, the coaches, the teams even, they all rotate, they all change; but some things do not change and are remarkably consistent year in and year out.
Those are the relevant things.