The "why should I care" is about 3/4 of the way down the page:

> None of these numbers are exact, but the structural gap is clear: a handful of nodes costing roughly $560/month versus $10,000-20,000/month for a managed service at the same scale. As we explained earlier, it’s practical to operate OpenData Timeseries yourself and fully realize these massive cost savings since it isn’t a traditional distributed database that manages partitioned and replicated state.

It doesn't look 100% turn-key, but those are compelling numbers.