Ever since then, I can't shake the feeling that I should probably turn it into a simple SaaS app.
It really made me think that nicely designed Google Sheets documents are probably the perfect way to prototype some applications. They're free, fast to build, and anyone can access them... And, apparently, you can get them to look pretty damn nice.
I couldn't agree more with you about Google docs for prototyping. A Google Sheet + Form (e.g. collecting signup emails) combination offers some serious potential.
I would like Sourceful to be a place where projects like that are promoted and initial discussion around them takes place. Twitter/Facebook are not ideal places for that as the content there is too ephemeral.
It appears that the use of this format has been growing, especially during the recent events (coronavirus pandemic, climate change then BLM protests).
I can't say a static webpage is any better, since that requires quite a bit of know-how, hosting costs, and other in-conveniences than just making the google doc public.
I also feel confused when celebrities et al. share their deep thoughts, apologies, outcries, and other information by screen-shotting a story written in their phone's notes app and posting the images, but there really isn't anything simpler and more reliable than that (since writing in non-native apps, especially iOS, tend to reset themselves and delete your text if you exit the app for too long).
Haven't thought about celebrities screen-shotting their thoughts but it's definitely a thing :) there could be something there.
Outside of Sourceful, to see what is the most viewed document on the web, the best way is to use a tool like ahrefs. However, the quality of the doc does not seem to be strongly correlated to this number as the top docs are often clickbait/practically useless.
If yes, is curation the value?
So there is a lot of added value in showcasing and promoting great docs which are not easy to find. Another area is giving feedback to the doc owner though commenting - the collaboration system in Google docs is not ideal for high-level discussion about the doc.