Drive vendors have been bringing this metric in over the last 4 years or so, but only for new drive models, which is why it���s taken a while for people to notice. It���s really not as bad as it sounds - much like with SSDs, you���re very unlikely to ever come close to the ���rated workloads��� in most use cases.
From what I���ve seen so far through my work, this rating is used to explain higher-than-datasheet failure rates, rather than rejecting warranty claims . If you push a drive rated for 550TB/year beyond that level, then the failure rate increases. This is the vendor claim, and it���s something I���ve seen born out over time too - our appliances with low disk usage have a low drive failure rate overall (in some cases, better than the datasheet rating for AFR), and the ones with higher disk usage have a much higher failure rate than the datasheet AFR.
What it does do is lead you pick drive models that make sense for your workload. If you know you���re going to stick some cold data on the drive and maybe refresh it once or twice a year, the drives rated for 100-180TB/year workload are perfectly fine. If you have a moderately busy system, then drives rated at 550TB/year are probably ok.
But if you are doing 500TB/year of writes and you pick a 180TB/year rated drive, don���t complain when your AFR creeps up. Overall, I think it���s a useful tool.