In Gorge, the spawn is in the centre of the map width-wise so attackers take all of the paths. Most people on this map seemed to totally ignore the right path.
I can definitely confirm this from experience. I thought that I couldn't push the right side because it split into two further directions, one of which was easily campable by RED Snipers and the other which offered a massive height advantage as well as an extra spawn exit for RED. While either of those might be true, I did notice BLU choosing the left route much more often, and it makes sense, since that seems to be noticeably closer to spawn.
Also, I have to agree that this is an outstanding map for just an A1, and it's always good to see another "Gorge-style" Attack/Defense map. It's kind of strange how out of the 9 official A/D maps, there are 5-6 different structures, including Dustbowl/Egypt's three two-point stages that increasingly favour RED, Snowplow's two three-point stages with a train, Gravel Pit's A/B/C structure, Degroot Keep's timed twist on Gravel Pit's formula, Steel's dynamic structure, and Gorge's linear, single-stage system. I guess the advantage of having multiple stages and/or non-linear points is that it adds a lot of replayability to a map, but considering that Gorge and Mountain Lab are two of the most well-regarded A/D maps, their linear structure is a proven success, and I'm surprised we haven't seen any more maps like them in the last six years.