There is always an IF to everything, so one has to make choices that maximizes returns and minimizes risk, based on requirements. The systems that are in place with these giant corporations are extremely robust, and they take into account all factors that can go wrong, and hence they have several levels of redundancy built into the system, far more than what the average individual is aware of, let alone capable of. More importantly, keeping them secure over the internet is an extremely complex affair, another area that they know better than anyone else.
Despite all that, things can still go wrong, but so can the tiny SD card inside the phone dying off without warning exactly when the other backups elsewhere do. So we leave the theoretical possibilities aside, and look at things more realistically when making choices. The convenience of having access to all files from any device, anytime and from anywhere is an extremely important consideration for me, without compromising security. So cloud subscriptions are the way to go.
I have more than 20,000 songs in just 1 folder. But when I copy them to my phone, all my music magically show up under the correct Album, Artist, Genre, and even Playlists too! I need to do NOTHING other than just copying the files from my computer to my phone (all files inside the Music folder, and no sub-folders). I can copy just what I want too (for example, only files from a given playlist. Show me how to do that using a file manager

). There are apps that let you do that and they are
far better and significantly faster than using Windows Explorer/ Mac Finder or any File Manager. It doesn't matter which music app I use, the songs I want always show up in the right place. The reason for this magic is
METADATA.
I have been using these files and my system (of managing files) for well over 10 years, and there has never been any corruption or anything that would make me reconsider the way I manage them. Most importantly, I don't have to depend on any app to have access to my music of choice at any given moment.
The metadata are INDEPENDENT of apps and platforms (Android, iOS, Windows, macOS or Linux). Every good music app on every platform can filter the music the way I want. The exact same concept applies to photos and videos too.
One has to acknowledge that technology is improving, and there are better tools as well as smarter, more efficient ways of getting things done. Windows Explorer/ Mac Finder are best left to handle non-media files alone. For media, use Media Management Apps.