In my opinion, Automatic1111 is more of a development tool to experiment with different pipelines on your local GPU, or an internal tool serving a few users.

OneDiffusion project aims to solve a very different problem, which is bringing a SD pipeline to serve production traffic and scale in the cloud. For example, configuring a large diffusion model to run on multi-GPU: https://huggingface.co/blog/deploy-deepfloydif-using-bentoml