I'll say again that this is a common misconception. My D500 raw images are quite viewable even using the CODEC built into Windows. And (one more time) because I have LightRoom set to use the "As Shot" camera values, both that software and the Nikon software present pleasantly viewable images from the beginning of the editing procesd.

If one chooses to handle the files differenrly, then yes, it is possible to make them appear as the washed out green cast images that we typically see presented here. But that is a choice, not a requirement.

The sensor in your camera responds by converting light energy into electrical voltage. It is not color sensitive. To successfully record color we place a color filter array over the sensor so that each pixel in the sensor receives either red filtered light, green filtered light or blue filtered light. The sensor output is analog voltage which is converted in the camera into numerical values. Those numerical values are all either red filtered, green filtered or blue filtered values. That data is saved and is your raw file.

It takes special software but if you can open a raw file without processing it in any way it'll look like the first illustration below. The inset is an enlargement that let's you see the color filter array. First job is to remove the color filter array and assign the right color to each pixel in the image. This is a mathematical interpolation process we call demosaicing. In the second image below the raw data has been demosaiced and a white point has been assigned that get's us into a normal brightness range. There's still lots to do.

Pause at this point and realize that the camera software has to do all of this in order to create the camera JPEG. ALL DIGITAL IMAGES ARE HEAVILY POST PROCESSED. Either the camera does it or some computer software does it and either you get involved in controlling that or not. The idea that a final JPEG from the camera is somehow less post processed is bunk.

In the third image below two more processing changes have been applied. An input profile for the specific camera has been assigned -- the processing software needs to know about the camera used so that it can apply camera specific adjustments. And the white balance for the photo has been applied. It's looking better but it's flat. Digital camera data is recorded linearly and that means very flat looking photographs. No adjustment for that has been applied yet.

In the fourth image below a tone curve has been applied. This tone curve is the default tone curve generated by the raw converter. This is the image you would see without doing any post processing except to set the white balance. The white balance stored in the raw file is the auto-WB value set by the camera and the camera screwed that up.

The fifth image below is the camera SOOC JPEG in which the camera got the white balance wrong. The camera was set to auto-WB and that big yellow wall tripped it up and it tanked. Using the raw converter in image number 3 I set the white balance manually.

In the final 6th image I used the software supplied by the camera maker (Nikon Z7 and Nikon NX Studio) to re-created the SOOC JPEG but with the auto-WB error corrected. The 6th image is what the camera would have created if I had taken the trouble to set a custom WB at the scene before taking the photo like a good JPEG shooter should.

The processed image #4 from the raw converter has more contrast and increased color saturation compared with the processed JPEG from the camera #6. This is a difference due to the camera input profiles and tone curves applied. The raw conversion software did it differently than the camera. Some folks will prefer one over the other. I would prefer a final result between the two. The camera result is weak and the raw converter result is overdone. Therefore I would want to intervene in either process. I can do that more easily and quickly and successfully using the raw converter rather than editing the camera JPEG.

I'll say again that this is a common misconception. My D500 raw images are quite viewable even using the CODEC built into Windows. And (one more time) because I have LightRoom set to use the "As Shot" camera values, both that software and the Nikon software present pleasantly viewable images from the beginning of the editing procesd.

If one chooses to handle the files differenrly, then yes, it is possible to make them appear as the washed out green cast images that we typically see presented here. But that is a choice, not a requirement.

Your raw files are viewable in the OS because you're viewing the camera processed JPEG. A version of the camera JPEG is embedded in every raw file for that very purpose.

In many processing apps like LR when you first see your raw files in a browser component of the app you're again likely viewing the embedded JPEG. LR will eventually get around to building it's own previews of your raw images and show you those in the library and once you process an image the preview will reflect your processing choices.

But in most cases when an unprocessed raw file is viewable it's the embedded camera JPEG that's being viewed.

Great examples above, thank you. You can also easily have the advantages of RAW without post processing by opening the manufacturer's free software (NX Studio, View-NX-I/Canon DPP4) and export or output to TIFF, or whichever is your preferred format. The photo will be rendered using your in-camera picture control settings. So, in the end, you don't lose THAT capability (to control your exposure options) and you retain the simplicity, as well as the ability to further do SOME enhancements. There is no need for one versus the other. JPEG is simply a step-down from the original captured data and is only useful to email/post to sites that impose limitations on size and format.