Yeah, it'd seem to be that way. From experience, I've had some value A-Data DDR3 1333Mhz which I replaced as soon as I found a nice deal. It didn't limit my CPU overclock ( though I didn't overclock by FSB ) but there was no overclocking potential in the RAM itself.
I don't know about other countries but in Poland that'd seem to be a common mistake. People tend to buy nice CPUs and GPUs, worse MBs, worse PSUs and crappy RAM. Then when they want to overclock they run into problems. With computers it's the same as with other stuff - you have to keep it all balanced.