Could you go into more detail - how is the half-bridge less capable? (I'm not familiar with ether device, but the ultimate solution seems like a sub-optimal solution to me?)

Essentially, it's a case of smaller device with less powerful CPU and less powerful routing offloads, but which happens to have a hardware offload for the specific use case that they needed offloading - PPPoE.

As the article itself mentions, hardware PPPoE is often present on lower shelf chips, but missing from higher end chips that in turn have more switching/routing capabilities.