Piracy is the most consistent and solid form of preservation, definitely. Well technically piracy is a subset of “DRM-free software” which is the true holy grail. To preserve software, it must be able to be copied instead of tied interminably to something perishable like a disc or single hard drive. And piracy needs to be happening during the release windows of the software, not “be respectful and wait 5 years” - the only reason retro console libraries are as well-kept as they are is because people were dumping games to play for free back in the day.

Those Wii redownloads are tied to specific console IDs, and those console NANDs are just as vulnerable to damage or deletion or loss as normal physical media is. They’re even worse than account-based DRM’d media since account-based media at least tolerates hardware damage or loss (but not account bans or service EOL). Thankfully, every digital purchase on Nintendo platforms other than Switch 2 is fully preserved and made available. This would be impossible if Nintendo’s anti-piracy measures had ever worked for an entire console generation. Switch 2 games, on the other hand, are currently “loseable”. You might be reasonably sure that Nintendo will never delist DK Bananza until (insert threshold where you think it’d be acceptable here) but game preservationists also care about game versions.