It’s not 100% Go, though. It forks a process that manages the sqlite file. Since the communication with it is written in go, it avoids using cgo.
You're right, there are use-cases where SQLite is not appropriate. But nothing beats the ease of installation/backup/maintenance of SQLite compared to server databases like MySQL or Postgres. Another point is development: For unit-tests, I found that initializing a SQLite database for each test-run is much easier (and faster) than having a VM that runs Postgres/MySQL/etc, which I have to spin up and tear down before/after each test run.
That's exactly what I thought, too. But, to my own surprise, it's as fast as CGO solutions, in most cases even faster. You may check here: https://github.com/cvilsmeier/sqinn-go-bench
I'd want a benchmark that is just select * from table, where table is a few gigabytes…