The assumption with using a full loom of cables is that all of the cables get everything right and fit perfectly with your components’ and speakers’ intrinsic sound. It just doesn’t work that way. There’s a dearth of cable manufacturers that have achieved this level of refinement. Still, it’s likely that a particular listener or their chosen components will beg for particular qualities that are usually found by mixing more than one brand of high quality cables.
This is really just a different way of saying what’s already been said. This topic really deserves a dedicated book, but I don’t think any experienced system builder wants to write it because of how many unique variables there are in a given system.