As I understand, SDL offers abstractions that let you make windows, handle input and audio much easier than doing so directly with the low level APIs provided by several operating systems.
However, it seems that a lot of games, both indie and AAA, don't use it, and I would like to know why. This makes me suspect that there may be areas where SDL is lacking, such as features, performance, or robustness, when compared to platform-specific APIs.
Apart from platform support, that is, considering only the platforms SDL supports, I do not understand what would keep a developer from using SDL for their game, since I feel like, based on my admittedly limited knowledge, it'd be much smarter to use SDL on the platforms that do support it.