I am a bit confused. If Buddha's last words say:

" Behold, O monks, this is my last advice to you. All component things in the world are changeable. They are not lasting. Work hard to gain your own salvation. "

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Why then in Vajrayana (Tibetan Buddhism) so much emphasizing on the guru and transmission?

I know it suppose to be the middle way, not too dependent on the Teacher and not too self reliant.

However I came across couple of talks and books where clearly is stated without spiritual friend/guru there is no way to achieve enlightenment. And at the same time Mahayana and Hinayana schools point to a different path, where there is everything is teacher and there is no difference between self and teacher. It is one. I don't mean to disregard any of them. It is just contradicting and I would like to hear your take on this. Thank you