There is nothing wrong with the good postdocs, it's the bad ones that are the problem.
1) a postdoctoral that doesn’t lead to a professorship is one where they are looking for someone to do work independently without being trained. Basically, a very senior grad student. You largely follow the law ultimes of grants written by the PI.
2) a postdoc leading to a position is one where you are trained in developing a research program, writing grants, giving career talks, etc.
The easiest way to make sure your postdoc falls in the latter category is to find an advisor with a track record of past postdoc a getting professor positions. If someone has been a professor for two-four decades and has few former postdocs who became professors, you are unlikely to get training to become a professor.