is beneficial when playing with above average mouse sens, so those 'nearly out of reach battles' become easy. then there is zoomsens, itl need tweaking too to suit ur config.
Anyways, you're right that he's been using 103 for a while.
He also selected a reasonable zoom fov (58.7?), and has zoom now bound to b and v. Whether he uses it or not I have no idea.
Personally I think those keys are difficult to reach from QWES unless you're hitting it with your thumb, which feels awkward. So yeah, no idea if he actually uses it or not.
For a long time he had zoomfov set to fov, and did not have zoom bound, strongly indicating that he didn't use zoom. So he certainly can get by without it.
i zoom when im rushing someone from a long way off so i can get that free damage before they turn around, but never any other time. i feel like it makes me move my mouse entirely too much and i hit far less if i go lower than 92 fov.