There are other options out there, though in many cases distribution is uneven. There are new specs like JSONFeed which many sites and feed readers support just in the last year.
There are also simpler methods than RSS now including the microformats-based h-feed which one can use to create a simple feed that many feed readers will support.
Part of RSS’s ubiquity is that it is simply so prevalent that most common CMSs still support it. The fact that the idea of RSS is so old and generally un-evolving means there isn’t a lot of maintenance involved once it’s been set up.