It eliminates the parting line at the block surface. It's been done by engine builders for years. It must make a difference, that and the other preparation I do before installing the seal I've never had a leak
I fought a small leak till I put sealer between the main and block. Had pan off 5 times new 408. I just put a dab of black RTV at the seal ends. Seems to work for me, but I have considered off setting the seal ends...