Most, not all, but most of the top recruited athletes in the country do end up being top picks in the NFL draft...
To get a STAR rating, you have to go to camps, get invites to other camps and travel. I do believe there are bias in some of the ratings between 3 and 4 star kids based on who they are choosing. If Zach Wilson was picking USC, I promise you he would have been a 4 star instead of a 3 star kid.
These recruiting prognosticators all spend their time at Camps. If they do go to games, it's to watch the 5 star kids. They won't spend their time at games for a 3 star kid... they'll maybe watch a couple highlights, but they'll only watch those depending how well you did at one of the camps.