As with anything, what you need to carry depends a lot on your personal preferences.
My purpose here is to take a minimalist approach and keep things simple, as simple as it can get, so that you travel light and get the maximum out of your trek. I firmly believe that the lighter you trek, the more you enjoy it. As with anything, what you need to carry depends a lot on your personal preferences. For example, I like to carry around my DSLR and lenses for most treks because I like taking pictures with them, so that’s a trade-off I am willing to live with. But the same may not apply to you.