what are the weaknesses of taoism?

Answer 1

It's a religion of inaction as oppose to action.
Meaning both good and bad happen regardless of your actions.
It's book is impossible to understand and was written by someone no one knows.

Basically a guy decided to abandon his home and left his servant some scriptures.
That's what it's based on.

Answer 2

that which is joined to its strengths, of course.