Yeah, you're super wrong about this. Manual mode helps you control the consistency of photos during a session. I've met very few wedding photographers (who incidentally work almost exclusively out of a studio) who are willing to risk letting the camera decide on exposure. You need to know what your shutter speed is so that you don't end up with blur from the subject or camera movement. You need to control ISO to reduce noise as much as possible (grainy black and white's aside). And most of the time, the aperture is being set in a very specific way to affect the depth of field.

Once you become accustomed to manual mode, it is much more reliable and equally as fast as other modes, with the benefit of knowing that the camera isn't interpreting some specular highlight in the background and under-exposing a bunch of images.

This all applies to the professional sports, news, and event photographers I know, as well as myself personally.

Further to this, there are many photographic effects (long exposure light trails and panning, capturing fast moving subjects etc.) that are done much more easily and don't often occur in a studio setting. I think that the technique you've suggested may be valid for a certain subset of shooters, but your understanding of the photographic profession in general is very shallow.