The best way to keep the purchased files is on optical disk, so you may as well buy the CD in the first place!
Optical disc is still the best archival medium there is for our digital data, much more reliable then magnetic and SSD drives and forget cloud storage...
It's a pity that so many articles are more about making a lot of noise rather than presenting the facts of the matter. Disc rot is almost entirely the provenance of CDs manufactured at Philips & Du Pont Optical UK Limited during 1989-1990, and was the result of "using a lacquer that was unable to withstand the long-term corrosive effects of the sulphur normally found in paper used for CD booklets and inserts." That is, it arises from substandard manufacturing, it is not a design deficiency, and is limited to a small number of manufacturers. The second largest offender (much smaller than PDO UK) was OPTI.ME.S. in Italy.
One label that was severely affected was Hyperion. Their "we will replace any such disc" policy can be found at Bronzing CD's - Hyperion Records. Pearl and ASV were the next two largest victims (counts are by number of different recordings, not numbers of CDs).
CDs will die when manufacturers no longer make the players. It will be beyond the capability of small manufacturers to make the necessary electronic and opto-mechanical components with large enough economies of scale to make it worth producing them, unlike record decks which are a relatively simple engineering problem to produce. Bluray players will go the same way, driven out by online streaming.
Digital archiving is now at a level that storage on optical media is in the decline.
While the majority of historical "disc rot" flaws came from the sources mentioned, long-running mass production too often entails incremental corner-cutting which tends to distribute the flaws at a relatively low percent.The question then becomes how to quantify a low-incidence, but still problematic degradation spread more evenly over the total production of optical disks.Put another way, say 1% of all optical discs are made with imperfections which under certain storage/operating conditions leads to premature disc rot...one or two manufacturers/production facilities will not be identifiable sources, as the 1% is spread across all labels and product lines.Since there are literally billions of optical discs in the consumers' hands, and more are produced each day, that's still a lot of discs that will fail sooner than the industry originally projected.
Infographic: The Rise and Fall of the Compact Disc
And that is just USA CD sales...
As for optical drives/discs being the "best" archival self-created storage... I leave it to others to assess as I have no dog in that fight.
Stability Comparison of Recordable Optical Discs—A Study of Error Rates in Harsh Conditions
If the entire AV/music industry adopted the free replacement of otherwise undamaged discs exhibiting rot, then you have an industry that recognizes, acknowledges and takes responsibility for the issue.That low-play-count, properly stored discs, not from the known sources quoted are still being destroyed by disc rot shows it is not an issue easily detected in the manufacturing QA systems.I'd bet there is nearly zero actual testing done in production, the assumption being that if the processes were "out of control" (a QA technical term for production where the faults routinely approach or exceed tolerances) there would be only flawed discs which wouldn't play at all when new.In theory, a production system "in control" can't produce flawed output... In theory... But the graphs above show the degradation of visually intact discs doesn't always result in complete failure, but a potentially significant reduction in quality of the bitstream produced.Music reproduction is all about signal/sound quality.
I doubt many hifi enthusiasts (let alone the general public) routinely, carefully inspect their discs for disc rot or even for manufacturing flaws which may lead to it. They notice it when the flaw/discolouration is blatantly obvious, or when the disc won't play properly.And if that disc was in the "1%" that a particular music label produced in a particular run, too bad for the consumer.
Optical discs were/are marketed to the public as being extremely durable and accurately/reliably produced.Maybe a case of over-promising and under-delivering, except it may take years or decades before the discs show the result of manufacturing/materials flaws.And since at least some discs which were gingerly handled and immaculately stored and still exhibited disc rot, I'd say the manufacturers are not exonerated. There is still enough complaints that there is a basic problem in the production stream, even if it is low %, seemingly random and intermittent.
I don't routinely use my stack of little handled, reasonably stored CDs, but it would be annoying if I needed to use one (some?) and found play problems.I guess I'd just spend $10 and buy a copy off the iTunes Store.