The thing I never understand about die-hard manual mode users is, the vast majority of them still rely on the camera's meter. Which means, all the user is really doing is deciding on either a shutter speed or aperture value, and then fiddling the camera dial to adjust the other parameter to the right value based on the camera meter reading....
...which is exactly what using the camera in A or S mode does. All you're doing is moving the knob yourself to set the camera to the right value (S or A, respectively) instead of having the camera do it for you automatically. There is no additional creative input here, and it's technically slower than using A or S because of the physical movement required. It might make it a little easier to dial in exposure compensation (vs. setting that by using the specific EV+/- function) but the photographer is still basing his/her exposure choices on the camera's meter reading.
Unless you're out there with an incident light meter, using Sunny 16 or some derivative, or some well-developed innate sense of light metering, going "full manual" for most is just an alternative way of configuring the camera controls. In some cases it is slower and less efficient, in other cases it's merely an alternative method of dialing in exposure compensation by "creatively" deciding the shot needs over or underexposure- which the A or S shooter can do just as well by dialing in EV+/-.
IMHO there is nothing more "pure", "legitimate", "hardcore", or "manly" about using M full-time. It's there and has some specific uses, but not absolutely "better" than any of the other modes the camera has (with the possible exception of the canned modes like "Auto" or "Sport" or "landscape").
Ruahrc