Meanwhile, flash has revolutionized storage. We saw at least a 95% reduction in query times on our DB servers when we switched from RAID5 15K SAS drives to RAID1 flash SSDs.
This, exactly this. HDD will work just fine for your grandparents, while everyone who appreciates performance has moved on to flash.
The increased low latency read speeds combined with data deduplication, compression and instant off-site replication simply can't be matched by legacy spinning drives. It that is technology that is available today. Assuming that RRAM, as mentioned in TFA, becomes a generic technology that replaces flash, you'll have all the advantages of flash without the (very few) disadvantages such as wear.