The immediately obvious and simple to handle on-disk format for everything I cared about was one of the things that convinced me to give it a try. Well-crafted exporters are great and all, but I really like being confident that I can convert it by hand even if the company ceases to exist.

Backups are easy too: you can very reasonably just rsync the library folder, and it'll be recoverable from that alone (I tried it! Worked great). You'll lose accounts and image-content search and iirc faces (possibly painful), but most of that is trivially rebuilt or not very interesting for single-person scenarios.