Actually, with Canon cameras, the reason the Raw "L" mode isn't as sharp as MRaw or SRaw is because of how the sensor (and Canon's way of processing sensor data) creates an image. It is NOT because you just cannot see the soft focus on the smaller image produced by an MRaw or SRaw due to not being able to zoom in as much.
Each "Pixel" in a 21.2 MP image from my 5D Mk ii is only one color (Red Green or Blue). The processor uses an algorithm to determine the actual color of that pixel by combining data from each of the pixels around it to create an "Estimate" of the color that pixel should be.
When you use SRaw or MRaw, each actual Pixel in the final processed image is using 2, 3 or more of those primary color "pixels" that create the 21.2 MP resolution of the sensor.
There is less blur between pixels at the "pixel peeping" level in a MRaw or SRaw because it is using a full RGB pixel combo to create each of the pixels in the final product. It SEES a full RGB pixel for each pixel instead of having to calculate a RGB pixel from R, G, or B plus data from others.
If your focus is sharp and you are using newer L lenses (such as 70-200 2.8IS II, second Gen L primes or zoom lenses), you should not see a sharpness difference between Raw, MRaw, and SRaw if they were processed the same way. "Zooming" in isn't why it is less sharp. Its processed differently.
If you are using consumer grade lenses or even "semi-pro" lenses, you are outshooting your glass with a 20+ MP sensor. The glass won't resolve that level of detail in older and/or consumer grade lenses.
So, with Canons at least, you should ALWAYS get a sharper image from MRaw or SRaw than you get from RAW