AI has zero need to see the renders (you are just wasting tokens) and that is why I built the Go version - I patched a lot of the PPTX code in my MCP server, as it happens.
I have had a lot of experience creating and editing PowerPoint slides with Claude recently. It always converts the file to a PDF using LibreOffice and then renders the PDF into images to see if everything went right and that no text has overflowed.
Of course AI can one-shot slides, but if you want good results where everything is aligned and has proper contrast you need a visual feedback loop
I'm not saying a pure API view won't work, but it will be a quality compromise compared to also having visual inspection
Not saying that LLMs can do this, but there are algorithms which can, and neural networks are universal function approximators, so it is plausible.