No longer correct for two of the newer Canon bodies. It's available on them in manual mode when using Auto ISO. It gives you the best of both worlds. Auto ISO to give you the "correct" exposure for a given aperture and shutter speed, and the ability to override the ISO, and therefore the exposure, by applying EC. Auto ISO still works with EC applied, but it takes the amount of compensation you've chosen into consideration. Traditionally in manual mode with auto ISO you would have less control over the exposure since whenever you changed the aperture or shutter speed Auto ISO would compensate for what the camera identified as the best exposure. You would have to manually select an ISO setting to get around that. With manual mode EC in Auto ISO it basically allows you to shape the ISO being applied without having to select explicit ISO settings. It's a very cool feature on my 7D2.

Both the 7D Mark II and the brand new 80D have it. I suspect it will be on the new 1Dx Mark II flagship as well. I shoot in manual mode and use EC quite often.

You are not really wrong, but your vision has not yet developed a great deal of depth or width.

What you described is perfect, for Manual Exposure mode with Auto ISO turned off. A great example, that few folks seem to catch on to, of when that works would be shooting a basketball or volleyball game. The lighting does not change from shot to shot, so there is no need to have any kind of automatic adjustment enabled. At the start of the game, determine the correct exposure, set aperture, shutter speed and ISO and then forget about it until halftime!

All the world does not happen on an evenly lit gymnasium floor! If you are walking down the street and may take a in shot bright sunshine one instant and then in the shadows of an alley the next... auto something is useful. Take your pick, auto aperture, shutter, or ISO... or all three. Now Exposure Compensation is essential!

Once anything in the Exposure Triangle is set automatically, the only way to manipulate it to the bias you choose is by setting EC up or down.