Or the parts of your system that don't have big data and no need for massively concurrent writes. And that's the vast majority of systems!
If you think the majority of systems require massively concurrent writes, I think you need to look a bit harder. SQLite is, after all, the most widely deployed database system, ever.
It was forced upon most of us(not me, I used BeOS then Debian then FreeBSD).
I deployed phoenix.