What causes 201xs HDDs to live less than 200xs ones?

Question

There is a common opinion (on forums and e-market aggregator websites) that nowadays HDDs live less than the ones from 200xs. I wonder

• if this opinion is true;
• are there any researches confirming or declining this statement;
• what are the causes of this fall of reliability (except obvious conspiracy-theoretic ones that HDD/SSD manufacturers need to make SSD more competitive to HDDs)

Answer 1

The best freely-available large sample research is that done by Backblaze, though it probably doesn't go back far enough.

They do a report every quarter, see https://www.backblaze.com/blog/hard-drive-failure-rates-q1-2017/ for starters