The "port" terminology is misleading; this is real SQLite, compiled from C to Go using https://gitlab.com/cznic/ccgo/-/tree/master/v4 (by the same author; this library is its most widely used application). The use case is that a lot of Go codebases prefer to completely eschew FFI because a lot of the nice properties of Go's tooling and whatnot (cross-compilation is trivial, binaries are automatically static on Linux, etc.) only hold if the entire build is pure Go.
So because of Go's design mistakes.