Probably because most consumer 'infrastructure' devices have razor-thin margins. This has two consequences: the vendor doesn't spend any time tweaking it, and s

Probably because most consumer 'infrastructure' devices have razor-thin margins. This has two consequences: the vendor doesn't spend any time tweaking it, and second, the CPU is too puny to run all the packets through; they go instead through a hardware packet accelerator. It may be able to do the same thing, but not by configuring 'tc'. This is also why openwrt only runs sensibly (if at all) on the more expensive boxes.