[throwaway9870]

The problem is that with short haul serial links there is a very small operating range where error correction works. Basically the difference between a working link (very low BER) and a link where even ECC is broken (high BER) is quiet small and adding ECC overhead is deemed an overall loss. These links have quite different characteristics from long-haul links that are dominated by ISI. One way to see this is to look at a waterfall plot and note how steep it is on short interconnects. There is a very small range between working fine and completely broken.