exactly the reason why it is a bad design.
I think the reason for this design is to muffle the sound of water splash or bubbles coming into the sump, as this section is usually completely enclosed. maybe for durso overflow, this will help, but is not needed for herbie.
The first generation eshopps sump feeds directly to the sock, and is partially enclosed to muffle any water splashing sound. I use this sump and durso and it muffles the water sound enough. The newer generation separated the drain to its own section, which can have detritus collect, defeating the purpose of the filter sock, at least partly.
feeding water directly to the sock is the right design, which is what you have.