Even with DDR3 (and probably DDR4) you can still swap bits within a byte lane, and bytes within a word/channel depending on the setup of the memory controller. Some things change, and some stay the same!
When you do a suspend-to-ram on a current x86 machine, it has to save the "scrambler seed" to CMOS so that it can decode the data it left stored in RAM.
I think this also helps mitigate the attack where the DRAM is chilled to make its contents less volatile, the machine is powered off, and the DRAM is then dumped in search of sensitive material.
Other RAMs/Flash with different interfaces (e.g. SPI) require a prefix command to be sent over the wire, so it's easier for them to implement things like chip id commands.