Ask HN: Why would I use Openrouter over something like DeepInfra directly?

As far as I understand it, OpenRouter is just routing to providers such as DeepInfra, Baseten, Fireworks, Together, etc, who already provide access to many open-weight models. If my goal is to just use open-weight models and maybe add an extra key for OpenAI or Anthropic when necessary, why wouldn't I just use one of these? What's the point of the 5 percent markup?