To some extent, that's happening. Some mainboard manufacturers overclock the chipsets slightly as default. Whether that's cheating is another matter, but as long as they don't go public with it it's at least sneaking!
My take would be that if the board is stable and you don't plan to overclock then there's no reason to be angry. On the other hand, if you bought the board thinking you would overclock a good performer you will probably be disappointed when you discover that the manufacturer has already eaten into the OC headroom.