On my 98 E320 (W210) I noticed that the alternator is located fairly low. With the splash guard in place it would help protect rain and snow from getting in the coils of the alternator.
As far as the remark "only disguises fluid leaks", that is why I do my own oil changes (by removing the drain plug) and take a good look around to inspect for fluid leaks, rubber boots, etc. This is something that you cannot get at a "fast oil change" facility.
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles