A lens hood cannot stop dust, dirt, grime, oil, grease, finger prints, water etc falling on the lens front element
Actually, a lens hood is superlative at stopping most of those things. Better than a filter, in fact.
No way! ... a lens front element, with a lens hood on, can still easily get scratches, grease, dirt and what not. But a filter on a the lens front element will ensure you don't easily get scratches, grease, dirt, dust grime etc on your front element. I agree that a lens hood provides additional protection (for both lens and the filter) from bumps, hits etc ... if I had to choose between a lens hood and a filter, I'd go with the filter, I can always use my hand or anything else to block light but I can't stop splashing sea water or other elements falling on my lens front elements without a filter.