Not only can there be the obvious kinds of performance benefits (no Python/extra process overhead, more focused optimized libraries, etc) to implementing someth

Not only can there be the obvious kinds of performance benefits (no Python/extra process overhead, more focused optimized libraries, etc) to implementing something yourself, you can also implement nice features like rolling window regressions that aren’t compatible with the mostly offline/batch APIs used in OSS and which can be baked directly into the production system. This is probably non-obvious to most newer practitioners unfamiliar with the broader systems their model operates in, because their mental models of what’s possible are constrained by the tools they’re familiar with.