The mini-rant below assumes that there is no level cap in this world. If there is one, his potential skyrockets.
The MC’s talent triples the experience required to level up but grants a consistent +1 to all attributes per level. In contrast, average individuals gain 2–5 attribute points per level, with luck increasing by 1 for everyone.
For the same total experience, others can level up multiple times and gain 6, 9, 12, or 15 attribute points, compared to MC's fixed 7. This makes the talent suboptimal, offering fewer attribute points than all but the worst-case scenario, and less than half as effective as the best case.
Though, they used the terms “attributes” and “abilities” interchangeably here, so I have no way of knowing what exactly they meant.