pretty much exactly what I'm doing lately, only different products (sauerkraut, fermented vegetables, kombucha).
The only "problem" with making a starter culture without regular yeast in the beginning is that there are many strains of wild yeasts living all around us, and we have no control over which one(s) innoculate the culture. I've read some yeasts can be a little bitter. Also, I think it would be hard to figure out how strong the culture is if making bread with it. Just like, a long time ago, people made their own lye by a process of pouring water over ashes until an egg would float in it (well, it's more involved than that, but basically...). So I'm sure some of their resulting soap was lye-heavy and strong. In other words, it does work, but maybe not reliably repeatable as far as breadmaking goes.
One side note that I didn't see mentioned--cover the product, something like a tightly woven lightweight cotton cloth such as a flour sack tea towel secured with a rubber band or string. Fruit flies LOVE ferments.
Great article, thanks for sharing! I'm glad to hear people are reaching out for ideas and learning new stuff. Fermentation is an amazing thing!