True, there is a great danger in dogmatism. That’s why Marxists emphasize the scientific and changing nature of our worldview. “Read theory” shouldn’t mean “just read Marx and Lenin” it means you should also read Mao, Amin, Horne, and so on. Read it critically, notice changes, notice contradictions and consider different perspectives.
Bookchin argues we toss out Marxism as a whole because not everything Marx says can have held up. However, Marxists recognize that and critique and change the theory. We adapt to our conditions. Bookchin denies the method of proletarian revolution which we still uphold because we see it worked. He does not see it worked because he accepts the anti-communist alternative history.