Mainline braids often have additional 'ingredients' like Kevlar added to make them more tougher, and can actually be more abrasive or cutting along the fishes flanks than a softer hooklink braid, although there are a couple of hooklink braids that I avoid as they are so darn 'sharp'.
For hooklinks I would only ever use a specific hooklink braid, and I haven't come away from the Kryston stable for them for years; If it ain't broke don't fix it, and Kryston has not let me down. They may be more expensive than other manufacturers, but when a spool of Merlin lasts 4 or 5 years (and I do tie a lot of rigs), and can be used neat or as part of a combi-rig, then I stick to what I know works. The only Kryston coated braid I don't feel comfortable with, is actually Jackal. I found, (me personally), that I was breaking the coating when I tied my knots, and so they would go a bit limp as the coating was damaged.
As for coated braids, they are stiffer until you strip them, which can improve resistance to abrasion, cutting and rubbing against snags etc, and possibly for the carp.
When it comes to braids, we use higher breaking strains than the mainline, simply because some are so thin that if used in lower strains and diameters, would cut the fishes mouth, so using the finest may not always be best.