Your [3] has a footnote quoting a Google book that reads "Modern DRAM systems are a good example of a case in which powerful error correction can be provided at a very low additional cost... The following machine generation at Google did include memory parity detection, and once the price of memory with ECC dropped to competitive levels, all subsequent generations have used ECC DRAM"
Well They made a big deal out of it and lots of PR out of not having use ECC, and only quietly adding back ECC and listed it out in a book that barely any one reads.
