The height of the docks you dock at and the freeboard of the boats you raft with may vary, but the shape of YOUR boat's hull doesn't, and that is what you are protecting, so I have never understood the need for adjustability. What we did was hang out fenders from stainless snap hooks or carabiners, with a large enough mouth to fit around our stanchion bases. set the fender height, knot it, and it's done forever. Hanging fenders is as simple as snapping the shackle around the stanchion, and no pressure on the lifelines.
To solve the rubrail chafe problem, wrap the lines in leather chafe guards.
From what I've seen in Maine, the Chesapeake, Jersy shore and the Carribean, the need for adjustability is more common in areas where you have a moderate tidal range vs. a large tidal range or very little.
In Maine with a large tidal range there is almot no fixed docks. It's all floating docks which are at consistent hight in reference to the water level. A 12 in. fender set at the waterline will work in most instances.
On the Chesapeake and Jersey shore with the moderate tidal range you get more of a mixture of fixed level docks and floating docks. With a fixed dock and a 3-4 ft tidal range you likely will need to adjust your fenders.
In the Carribbean with a small tidal range if you at the same fixed dock all the time you may not need any adjustments. However the distance between the water level and the fixed level of all docks you might visit could vary requiring an adjustment in fender position.