It doesn't. Compare an FTb to an A-1 and you immediately see the difference.
I'm amazed by the comments.
I'm a Canon freak and i've owned or own:
AE-1
A-1
EF
FT
F-1
New F-1
The A-1, in manual mode, shows you the selected shutter speed and the suggested aperture. So you do have metering and you do have manual exposure control. And it shows "M" while at it, so you are told you're in manual mode and the aperture shown is the meter output, not the actual aperture.
The FT and FTb (earlier versions) can do match needle, but once you have matched, they don't show you the shutter speed on the display yet nobody complains. At least the A-1 show you the speed you're at. Plus the A-1 meter is far quicker, far more sensitive and does not suffer from memory effects.
The EF show you exactly the same info as the A-1 when in manual mode, yet nobody complains (the EF is the most coveted of the FD bodies along with the T90 and New F-1)
Any well-liked meterless manual camera like the Leica M3 or Nikon F operate exactly like the A-1 when in manual mode, and nobody complains about them, yet the A-1 shows you the shutter speed and the suggested aperture.
The A-1 was made primarily as an auto camera. It has memory lock, exposure compensation, an extremely sensitive and reliable meter, and a viewfinder display that is very easy on the eyes and
can be disabled for you to concentrate fully on the picture. It also, like all A-series camera, have a soft electromagnetic release button and a very smooth mirror and shutter action (something that is often overlooked when evaluating the A-series cameras. They have one of the most smooth shutter and mirror mechanisms of all cameras.) It also has the most intuitive way of changing between P, Tv, Av and Manual modes of any camera i've handled. You can know which mode you're at just by feeling with your fingers...
I owned an A-1 for years, sold pictures made with it, used it in auto mode and in manual mode, and had no complaints regarding manual mode. My only complaints were regarding battery life !