Dall-E so far hasn't been able to grow an ecosystem because of how restricted it is. Meanwhile Stable Diffusion makes trial-and-error and innovation around it easy, and as a result only 9 days after Stable Diffusion's release we see OpenAI release a feature that looks like a copy of a tool from the Stable Diffusion ecosystem.

I agree that Dall-E isn't obsolete. I'd also add MidJourney to that list. All three are great models in their own right with their own pronounced strengths and weaknesses. But when it comes to enabling novel workflows Stable Diffusion seems lightyears ahead of the others.