This could be a very long answer so will try to contain myself.
Generally, I agree with the initial sentiments. An image is not what is front of you, it is what you make of it. It is how you control and use the light and how you see the subject and what you include and exclude from the frame.
There are of course a plethora of photographic styles and some are based on PP (post processing).
If we just think about standard digital images, then all photos are processed. This is usually by a camera to a set of default settings. This was the same with film choice previous to this.
Post processing to me is just taking control of the processing. Sure, it’s not easy, sure it takes skill to do well, sure it’s easy to do badly but if you want a photograph to really be yours then you have to do it. This is just the same as if you were a film tog back in the day.
…the same goes for filters. If you use ND or ND grad filters for landscape images then they all have a colour cast to a greater of lesser extent so PP is actually a more pure way of processing the shots.
…okay kept that fairly brief but that’s my 2c.