I just recently learned about it and it is for aesthetic purposes generally speaking. Some of these types of modifications are available through a graphics cards' native "control panel" programs (e.g., overriding a program's native anti-aliasing settings) but Reshade offers a variety of extra functions. I'm not sure that it would provide an advantage but I think it may do something to the client to access the shaders. I don't really know enough about the technical processes involved.
Here is another post from about a year ago
https://www.project1999.com/forums/s...d.php?t=246796 that seems to suggest the guy had already tried running reshade (or some aspect of it)